Developer Utilities
Small developer utilities that save a trip to a random website. Encode and decode Base64, explain a regex, build UTM links, generate QR codes and vCards, and more — the everyday helpers. Free in your browser, and available by API when you need them in a script.
Developer Utilities
Generate a UUID
v4, v7 or ULID, free in your browser
POST /dev/uuid$0.002Developer Utilities
Hash a string
SHA-256, SHA-512, MD5 or SHA-1, free
POST /dev/hash$0.002Developer Utilities
Sign and verify a payload
HMAC, free in your browser
POST /dev/hmac$0.002Developer Utilities
Decode a JWT
read the claims and verify the signature
POST /dev/jwt-decode$0.002Developer Utilities
Create a signed JWT
HS256 or RS256, free in browser
POST /dev/jwt-sign$0.002Developer Utilities
Generate a 2FA code
TOTP authenticator codes, free
POST /dev/totp$0.002Developer Utilities
Encrypt text
AES-256-GCM, your key, never stored
POST /dev/encrypt$0.002Developer Utilities
Generate a password
strong and random, free in browser
POST /dev/password-gen$0.002Developer Utilities
Encode and decode Base64
standard or URL-safe, free
POST /dev/base64$0.002Developer Utilities
Encode and decode a URL
percent-encoding done right
POST /dev/url-encode$0.002Developer Utilities
Make a URL slug
clean slugs from any language, free
POST /dev/slug$0.002Developer Utilities
Convert between time zones
DST handled right, free
POST /dev/timezone$0.002Developer Utilities
Convert a Unix timestamp
epoch to date and back, free
POST /dev/epoch$0.002Developer Utilities
Count business days
with holidays for 100+ countries
POST /dev/business-days$0.002Developer Utilities
Explain a cron expression
in plain words, free
POST /dev/cron-explain$0.002Developer Utilities
See the next cron runs
the next N times, free in browser
POST /dev/cron-next$0.002Developer Utilities
Schedule a webhook
cron without a server, published price
POST /dev/cron-webhook$0.002Developer Utilities
Schedule a delayed callback
in 30 minutes or 30 days
POST /dev/delay$0.002Developer Utilities
Shorten a link
on your own domain, published price
POST /dev/short-url$0.002Developer Utilities
Track link clicks
referrers and geography, per link
POST /dev/short-url-stats$0.002Developer Utilities
Make a QR code
URL, WiFi, vCard or text, free
POST /dev/qr-generate$0.002Developer Utilities
Add a logo to a QR code
branded and still scannable
POST /dev/qr-logo$0.002Developer Utilities
Edit a QR after printing
change where it points, priced
POST /dev/qr-dynamic$0.002Developer Utilities
Read a QR code
decode it from an image, free
POST /dev/qr-decode$0.002Developer Utilities
Make a barcode
EAN, UPC, Code128, Code39 or ITF, free
POST /dev/barcode-generate$0.002Developer Utilities
Read a barcode from a photo
scan it, published price
POST /dev/barcode-decode$0.002Developer Utilities
Create a vCard
standards-compliant contact cards, free
POST /dev/vcard$0.002Developer Utilities
Create a calendar invite
works in every client, free
POST /dev/ical$0.002Developer Utilities
Build UTM campaign links
consistent and parseable, free
POST /dev/utm$0.002Developer Utilities
Generate a regex
describe it, get the pattern and tests
POST /dev/regex-generate$0.003Developer Utilities
Explain a regex
understand the pattern you inherited
POST /dev/regex-explain$0.003Developer Utilities
Explain code
a function in plain language, priced by size
POST /dev/code-explain$0.003Developer Utilities
Document your code
docstrings and docs from source
POST /dev/code-document$0.003Developer Utilities
Turn a question into SQL
a query against your schema
POST /dev/text-to-sql$0.003Developer Utilities
Generate a JSON Schema
inferred from example payloads
POST /dev/json-schema-gen$0.003Developer Utilities
Generate unit tests
including the edge cases you forgot
POST /dev/unit-tests$0.003Developer Utilities
Write a commit message
conventional commits from a diff
POST /dev/commit-message$0.003Developer Utilities
Generate a README
a real one from your repository
POST /dev/readme$0.003Developer Utilities
Reshape a webhook payload
between two systems, free
POST /dev/webhook-transform$0.002Developer Utilities
Sign and verify webhooks
outgoing and incoming, free
POST /dev/webhook-sign$0.002Developer Utilities
Run hundreds of HTTP requests
fan out, collect results
POST /dev/http-batch$0.002Developer Utilities
Generate placeholder text
actually about your topic
POST /dev/lorem$0.003Developer Utilities
Subnet calculator
CIDR, mask, hosts and ranges, free
POST /dev/subnet$0.002Developer Utilities
Remove tracking parameters from a URL
see exactly what changed
POST /dev/url-clean$0.002Developer Utilities
Date difference and age calculator
years, months and exact days
POST /dev/date-diff$0.002Developer Utilities
Regex tester
match and replace online, free in your browser
POST /dev/regex-tester$0.002Developer Utilities
Fraction calculator
simplify, add, multiply free in your browser
POST /dev/fraction-calculator$0.002Developer Utilities
Percentage calculator
free online in your browser
POST /dev/percentage$0.002Developer Utilities
Base converter
binary hex free in browser
POST /dev/number-base$0.002Developer Utilities
Roman numeral converter
free in your browser
POST /dev/roman$0.002Developer Utilities
GCD LCM calculator
free in your browser
POST /dev/gcd-lcm$0.002Developer Utilities
BMI calculator
free online in your browser
POST /dev/bmi$0.002Developer Utilities
VAT calculator
add or extract tax free online
POST /dev/vat-calculator$0.002Developer Utilities
Sleep calculator
bedtime by 90-min cycles free
POST /dev/sleep-calculator$0.002Developer Utilities
TDEE & BMR calculator
Mifflin free online
POST /dev/calorie-needs$0.002Developer Utilities
Grade calculator
weighted average free online
POST /dev/grade-calculator$0.002Developer Utilities
Salary calculator
hourly to annual free online
POST /dev/salary-calculator$0.002Developer Utilities
Aspect ratio calculator
free online
POST /dev/aspect-ratio$0.002Developer Utilities
CAGR calculator
compound annual growth free
POST /dev/cagr$0.002Developer Utilities
Circle calculator
radius area free online
POST /dev/circle$0.002Developer Utilities
Ohm's law calculator
V I R P free online
POST /dev/ohm-law$0.002Developer Utilities
One rep max calculator
Epley Brzycki free
POST /dev/one-rep-max$0.002Developer Utilities
Profit margin calculator
free online
POST /dev/profit-margin$0.002Developer Utilities
Simple interest calculator
free online
POST /dev/simple-interest$0.002Developer Utilities
Download time calculator
free online
POST /dev/download-time$0.002Developer Utilities
Discount calculator
percent off and final price free in your browser
POST /dev/discount-calculator$0.002Developer Utilities
Time calculator
hours, minutes and seconds free in your browser
POST /dev/time-calculator$0.002Developer Utilities
Body fat calculator
US Navy free
POST /dev/body-fat$0.002Developer Utilities
Break even calculator
free online
POST /dev/break-even$0.002Developer Utilities
Cat age calculator
free online
POST /dev/cat-age$0.002Developer Utilities
Dog age calculator
free online
POST /dev/dog-age$0.002Developer Utilities
Due date calculator
free online
POST /dev/due-date$0.002Developer Utilities
GPA calculator
free online
POST /dev/gpa-calculator$0.002Developer Utilities
Heart rate zones
Karvonen free online
POST /dev/heart-rate-zones$0.002Developer Utilities
Ideal weight calculator
free online
POST /dev/ideal-weight$0.002Developer Utilities
Ovulation calculator
free online
POST /dev/ovulation-calculator$0.002Developer Utilities
Speed distance time calculator
free
POST /dev/speed-distance-time$0.002Developer Utilities
Water intake calculator
free online
POST /dev/water-intake$0.002Developer Utilities
Fuel cost calculator
trip cost free in your browser
POST /dev/fuel-cost$0.002Developer Utilities
chmod calculator
rwx to octal free in your browser
POST /dev/chmod-calculator$0.002Developer Utilities
Quadratic equation solver
roots free in your browser
POST /dev/quadratic-equation$0.002Developer Utilities
Pythagorean theorem calculator
free in your browser
POST /dev/pythagoras$0.002Developer Utilities
EV charge time calculator
free online
POST /dev/ev-charge-time$0.002Developer Utilities
Inflation calculator
free online
POST /dev/inflation-calculator$0.002Developer Utilities
A1C converter
educational ADA free
POST /dev/a1c-converter$0.002Developer Utilities
BAC calculator
educational estimate, free online
POST /dev/bac-calculator$0.002Developer Utilities
Dew point calculator
free online
POST /dev/dew-point$0.002Developer Utilities
Heat index calculator
NWS free online
POST /dev/heat-index$0.002Developer Utilities
Macro calculator
protein carbs fat free
POST /dev/macro-calculator$0.002Developer Utilities
Moon phase calculator
free online
POST /dev/moon-phase$0.002Developer Utilities
Plate calculator
barbell loading free
POST /dev/plate-calculator$0.002Developer Utilities
Tire size calculator
diameter free online
POST /dev/tire-size$0.002Developer Utilities
Permutation & combination calculator
free in your browser
POST /dev/permutation-combination$0.002Developer Utilities
Resistor color code calculator
free in your browser
POST /dev/resistor-color-code$0.002Developer Utilities
ROI calculator
return on investment free in your browser
POST /dev/roi$0.002Developer Utilities
Bell number calculator
free
POST /math/bell-number$0.002Developer Utilities
Equilateral triangle calculator
free
POST /math/equilateral-triangle$0.002Developer Utilities
Euler triangle OI distance calculator
free
POST /math/euler-triangle-formula$0.002Developer Utilities
Intersecting chords calculator
free
POST /math/intersecting-chords$0.002Developer Utilities
Jacobsthal number calculator
free
POST /math/jacobsthal-number$0.002Developer Utilities
Oblique cylinder calculator
free online
POST /math/oblique-cylinder$0.002Developer Utilities
Spherical excess calculator
Girard free
POST /math/spherical-excess$0.002Developer Utilities
Subfactorial calculator
free
POST /math/subfactorial$0.002Developer Utilities
Torus sector calculator
free
POST /math/torus-sector$0.002Developer Utilities
Tribonacci number calculator
free
POST /math/tribonacci-number$0.002Developer Utilities
Trirectangular tetrahedron calculator
free
POST /math/trirectangular-tetrahedron$0.002Developer Utilities
Break even occupancy calculator
free
POST /finance/break-even-occupancy$0.002Developer Utilities
Capital gains tax estimator
free
POST /finance/capital-gains-tax$0.002Developer Utilities
DSCR calculator
free
POST /finance/debt-service-coverage$0.002Developer Utilities
FHA MIP calculator
free
POST /finance/fha-mip$0.002Developer Utilities
FIRE number calculator
free
POST /finance/fire-number$0.002Developer Utilities
Hard money loan calculator
free
POST /finance/hard-money-loan$0.002Developer Utilities
Interest capitalization calculator
free
POST /finance/interest-capitalization$0.002Developer Utilities
Mortgage recast calculator
free
POST /finance/mortgage-recast$0.002Developer Utilities
One percent rule calculator
free
POST /finance/one-percent-rule$0.002Developer Utilities
Rule of 78 rebate calculator
free
POST /finance/rule-of-78-rebate$0.002Developer Utilities
SS claim breakeven calculator
free
POST /finance/ss-claim-breakeven$0.002Developer Utilities
French Republican calendar
free
POST /date/french-republican$0.002Developer Utilities
Interval intersection
free
POST /date/interval-intersection$0.002Developer Utilities
Juche era converter
free
POST /date/juche$0.002Developer Utilities
Julian ↔ Gregorian converter
free
POST /date/julian-calendar$0.002Developer Utilities
Leap seconds UTC↔TAI
free
POST /date/leap-seconds$0.002Developer Utilities
NTP ↔ Unix timestamp
free
POST /date/ntp-timestamp$0.002Developer Utilities
Parse relative dates
free
POST /date/relative-parse$0.002Developer Utilities
Roman Kalends/Nones/Ides
free
POST /date/roman-date$0.002Developer Utilities
UUID v1/v6/v7 to timestamp
free
POST /date/uuid-time$0.002Developer Utilities
Weekday occurrence in month
free
POST /date/weekday-occurrence$0.002Developer Utilities
Sphere calculator
volume and surface free in your browser
POST /dev/sphere$0.002Developer Utilities
Voltage divider calculator
free in your browser
POST /dev/voltage-divider$0.002Developer Utilities
Polygon apothem calculator
free
POST /math/polygon-apothem$0.002Developer Utilities
Taxable equivalent yield calculator
free online
POST /finance/taxable-equivalent-yield$0.002Developer Utilities
Abjad numeral converter free online
POST /math/abjad-numerals$0.002Developer Utilities
Age ratio calculator
present and future ages free
POST /math/age-ratio$0.002Developer Utilities
Boat and stream speed calculator free online
POST /math/boat-stream$0.002Developer Utilities
CP SP MP calculator
cost selling marked price free
POST /math/cp-sp-mp$0.002Developer Utilities
Hebrew numeral converter and gematria free
POST /math/hebrew-numerals$0.002Developer Utilities
Largest remainder seat allocation free
POST /math/largest-remainder$0.002Developer Utilities
Maya vigesimal numeral converter free
POST /math/maya-numerals$0.002Developer Utilities
Pie chart angles from values free online
POST /math/pie-chart-angles$0.002Developer Utilities
Pipes and cisterns calculator free online
POST /math/pipes-cisterns$0.002Developer Utilities
Sainte-Laguë seat allocation calculator free
POST /math/sainte-lague$0.002Developer Utilities
Orthodox Christmas date
free
POST /date/orthodox-christmas$0.002Developer Utilities
Victoria Day (Canada) date
free
POST /date/victoria-day-ca$0.002Developer Utilities
Week of month calculator
free
POST /date/week-of-month$0.002Developer Utilities
CD early withdrawal penalty
free
POST /finance/cd-early-penalty$0.002Developer Utilities
Lease buyout cost
free
POST /finance/lease-buyout-cost$0.002Developer Utilities
Mortgage offset account savings
free
POST /finance/mortgage-offset$0.002Developer Utilities
Negative equity roll-in
free
POST /finance/negative-equity-rollin$0.002Developer Utilities
Mortgage points break-even
free
POST /finance/points-breakeven$0.002Developer Utilities
Prepayment penalty calculator
free
POST /finance/prepayment-penalty$0.002Developer Utilities
Quarterly estimated tax
free
POST /finance/quarterly-estimated-tax$0.002Developer Utilities
Standard vs itemized deduction
free
POST /finance/standard-vs-itemized$0.002Developer Utilities
Gall–Peters projection calculator
free
POST /geo/gall-peters$0.002Developer Utilities
Geocentric radius calculator
free
POST /geo/geocentric-radius$0.002Developer Utilities
Vertical sextant angle distance
free
POST /geo/vertical-sextant-angle$0.002Developer Utilities
Arithmetico-geometric series sum
free
POST /math/arithmetico-geometric-series$0.002Developer Utilities
Chain discount / net price factor
free
POST /math/chain-discount$0.002Developer Utilities
Hexagonal prism calculator
free
POST /math/hexagonal-prism$0.002Developer Utilities
Markdown percentage calculator
free
POST /math/markdown-percent$0.002Developer Utilities
Motzkin number calculator
free
POST /math/motzkin-number$0.002Developer Utilities
Power of a point calculator
free
POST /math/power-of-a-point$0.002Developer Utilities
Regular tetrahedron calculator
free
POST /math/regular-tetrahedron$0.002Developer Utilities
Roman chronogram calculator
free
POST /math/roman-chronogram$0.002Developer Utilities
Square pyramid calculator
free
POST /math/square-pyramid$0.002Developer Utilities
Stair rise and run calculator
free
POST /math/stairs-rise-run$0.002Developer Utilities
Tangent-secant theorem calculator
free
POST /math/tangent-secant-theorem$0.002Developer Utilities
Wastage allowance calculator
free
POST /math/wastage-allowance$0.002Developer Utilities
Hedges g effect size
free
POST /stat/hedges-g$0.002Developer Utilities
Matthews correlation (MCC)
free
POST /stat/matthews-corr$0.002Developer Utilities
Haversine distance - great-circle km, mi and m between two points
POST /geo/haversine$0.002Developer Utilities
Absolute value equation solver
solve |ax+b|=c for x
POST /algebra/absolute-value-equation$0.002Developer Utilities
Finite series partial sum
accumulate terms, free
POST /algebra/partial-sum-series$0.002Developer Utilities
2×2 system by substitution
isolate, solve, free
POST /algebra/system-2x2-substitution$0.002Developer Utilities
Kepler's third law calculator
find period or radius from a known orbit
POST /astro/kepler-third-law$0.002Developer Utilities
Physical size from angular diameter
small-angle calculator
POST /astro/physical-size-from-angular$0.002Developer Utilities
Propellant mass fraction calculator
delta-v and exhaust velocity
POST /astro/propellant-mass-fraction$0.002Developer Utilities
Limiting reactant calculator
which reactant runs out first
POST /chem/limiting-reactant$0.002Developer Utilities
Moles of product calculator
reactant moles and mole ratio
POST /chem/moles-of-product$0.002Developer Utilities
Electrolysis overpotential calculator
applied vs thermodynamic voltage
POST /chem/overpotential$0.002Developer Utilities
Percent yield calculator
actual over theoretical yield
POST /chem/percent-yield$0.002Developer Utilities
Darken a hex color by percentage
lower lightness, free
POST /color/darken$0.002Developer Utilities
RGB to CMYK converter
print percentages, free online
POST /color/rgb-cmyk$0.002Developer Utilities
Binomial coefficients row
n choose 0…n as BigInt, free
POST /combo/binomial-row$0.002Developer Utilities
Decibel ratio converter
dB to power or amplitude linear ratio
POST /conv/decibel-ratio$0.002Developer Utilities
Electrical conductivity converter
S/m, S/cm, mho/m, free
POST /conv/electrical-conductivity$0.002Developer Utilities
Convert equivalent dose
Sv, mSv, µSv, rem, free
POST /conv/equivalent-dose$0.002Developer Utilities
HP to kW converter
horsepower to kilowatts, exact factor
POST /conv/hp-to-kw$0.002Developer Utilities
Length converter
meters, km, miles, feet, inches, yards
POST /conv/length$0.002Developer Utilities
Convert mass moment of inertia
kg·m², g·cm², lb·ft², free
POST /conv/moment-of-inertia$0.002Developer Utilities
Pressure gradient converter
Pa/m, psi/ft, bar/m and more
POST /conv/pressure-gradient$0.002Developer Utilities
Stone to lbs converter
exact 14 lb factor, free online
POST /conv/stone-to-lbs$0.002Developer Utilities
Temperature converter
Celsius, Fahrenheit, Kelvin, Rankine
POST /conv/temperature$0.002Developer Utilities
Add working days to a date
skip weekends, free
POST /date/add-workdays$0.002Developer Utilities
US daylight saving start date
second Sunday of March, free
POST /date/daylight-saving-start-us$0.002Developer Utilities
Days elapsed in the quarter
count whole days from quarter start
POST /date/days-elapsed-quarter$0.002Developer Utilities
Easter Sunday date
Gregorian computus for any year
POST /date/easter$0.002Developer Utilities
Generation by birth year
Millennial, Gen Z, Boomer and more
POST /date/generation-cohort$0.002Developer Utilities
Battery runtime from Ah
capacity, load current, and usable DoD
POST /elec/battery-runtime-ah$0.002Developer Utilities
Capacitor voltage rating selector
derate working voltage to a standard rating
POST /elec/capacitor-voltage-rating$0.002Developer Utilities
Drift velocity calculator
find vd from current, n, A and q
POST /elec/drift-velocity$0.002Developer Utilities
Transformer turns ratio calculator
Np/Ns and voltages, free
POST /elec/transformer-turns$0.002Developer Utilities
Damm check digit
compute and validate, catch typos free
POST /enc/damm$0.002Developer Utilities
Keyword substitution cipher
encrypt & decrypt online, free
POST /enc/keyword-cipher$0.002Developer Utilities
Scytale cipher
encrypt or decrypt with a column transposition
POST /enc/scytale$0.002Developer Utilities
encodeURIComponent tool
encode and decode URI components, free
POST /enc/url-component$0.002Developer Utilities
UTF-16 code unit converter
encode or decode hex, free
POST /enc/utf16$0.002Developer Utilities
Octal to decimal converter
base-8 string to integer, free
POST /fmt/octal-decimal$0.002Developer Utilities
Cardinal to ordinal number converter
1st, 2nd, 3rd, free
POST /fmt/ordinal$0.002Developer Utilities
Initial bearing calculator
forward azimuth between two coordinates
POST /geo/bearing$0.002Developer Utilities
Crosswind component calculator
wind speed and angle, free
POST /geo/crosswind-component$0.002Developer Utilities
Geohash encoder
latitude and longitude to a compact string
POST /geo/geohash-encode$0.002Developer Utilities
Geographic midpoint calculator
great-circle halfway point free
POST /geo/midpoint$0.002Developer Utilities
Geographic polygon perimeter
great-circle length of a lat/lon ring
POST /geo/polygon-perimeter$0.002Developer Utilities
Pythagorean equirectangular distance
approximate ground metres between two points
POST /geo/pythagorean-geo-distance$0.002Developer Utilities
Capsule volume & surface area
stadium of revolution, free
POST /geom/capsule$0.002Developer Utilities
Hyperbola eccentricity
from semi-axes a and b, free
POST /geom/hyperbola-eccentricity$0.002Developer Utilities
Polygon interior angle calculator
sum, exterior & per-angle
POST /geom/polygon-interior-angle$0.002Developer Utilities
Star polygon area calculator
regular {n/d} area from points, density, radius
POST /geom/star-polygon-area$0.002Developer Utilities
Triangle incenter calculator
incenter and inradius from vertices
POST /geom/triangle-incenter$0.002Developer Utilities
Mifflin-St Jeor BMR calculator
basal metabolic rate from weight, height, age and sex
POST /health/bmr-mifflin$0.002Developer Utilities
Caffeine dose by body weight
mg from mg/kg target, free
POST /health/caffeine-per-kg$0.002Developer Utilities
eGFR kidney function calculator
CKD-EPI creatinine free
POST /health/egfr$0.002Developer Utilities
Fat mass from body fat %
convert weight and percent to kg
POST /health/fat-mass-from-percent$0.002Developer Utilities
Ponderal index calculator
mass over height cubed, free
POST /health/ponderal-index$0.002Developer Utilities
Metronome subdivision calculator
duration in ms and frequency from tempo
POST /hobby/metronome-subdivision$0.002Developer Utilities
Home circuit count calculator
lighting & outlets from sq ft
POST /home/circuit-count$0.002Developer Utilities
Metal roofing panel calculator
panels from roof area and overlap
POST /home/metal-roofing-panels$0.002Developer Utilities
Sod calculator
rolls and pallets from lawn area and waste
POST /home/sod$0.002Developer Utilities
Harmonic series calculator
n-th partial sum H_n
POST /math/harmonic-series$0.002Developer Utilities
Prime factorization
break any integer into primes and exponents
POST /math/prime-factorization$0.002Developer Utilities
Projectile range calculator
speed, angle and gravity, free
POST /mech/projectile-range$0.002Developer Utilities
Time of flight calculator
projectile launch speed, angle, gravity
POST /mech/projectile-time-of-flight$0.002Developer Utilities
Simple pendulum period
T = 2π√(L/g) online
POST /mech/simple-pendulum$0.002Developer Utilities
Flywheel spin-down time
inertia, speed, and braking torque
POST /mech/spin-down-time$0.002Developer Utilities
List all ordered compositions of an integer
free
POST /numth/compositions-list$0.002Developer Utilities
Discrete logarithm solver
baby-step giant-step mod p
POST /numth/discrete-log$0.002Developer Utilities
Divisors of a number
list, count and sum, free
POST /numth/divisor-list$0.002Developer Utilities
Is prime checker
trial division and Miller–Rabin, free
POST /numth/prime-checker$0.002Developer Utilities
Acoustic resonance Q factor calculator
f0 over half-power bandwidth
POST /optics/acoustic-resonance-q-factor$0.002Developer Utilities
Lensmaker's equation
focal length from n, R1, R2
POST /optics/lensmaker$0.002Developer Utilities
Wavelength calculator
speed divided by frequency, free
POST /phys/wavelength$0.002Developer Utilities
Durbin-Watson statistic calculator
first-order residual autocorrelation
POST /stat/durbin-watson$0.002Developer Utilities
Tukey HSD post-hoc
pairwise comparisons after ANOVA, free
POST /stat/tukey-hsd$0.002Developer Utilities
Reverse line order
flip text lines top to bottom, free
POST /str/reverse-lines$0.002Developer Utilities
Charles's law calculator
find V2 or T2 at constant pressure
POST /thermo/charles-law$0.002Developer Utilities
EV trip charging cost
distance, efficiency, and electricity price
POST /travel/ev-trip-cost$0.002Developer Utilities
Half-angle calculator
sin, cos, tan of half the angle with correct signs
POST /trig/half-angle$0.002Developer Utilities
Rectangular to polar converter
r and theta in the correct quadrant
POST /trig/rectangular-to-polar$0.002Developer Utilities
Midline of a sinusoidal function
find y = D from the vertical shift
POST /trig/sinusoid-midline$0.002Developer Utilities
EMC field strength converter
V/m, dBµV/m, A/m, free
POST /conv/emc-field-strength$0.002Developer Utilities
First-order reaction time calculator
t = ln([A]₀/[A])/k, free
POST /chem/first-order-time$0.002Developer Utilities
Absorbed dose converter
Gy, mGy, rad and erg/g, free
POST /conv/absorbed-dose$0.002Developer Utilities
Acceleration converter
m/s², ft/s², g and gal, free
POST /conv/acceleration$0.002Developer Utilities
Mole unit converter
mol, mmol, µmol, kmol and lb-mol, free
POST /conv/amount-of-substance$0.002Developer Utilities
Angle converter
degrees, radians, gradians, turns, free
POST /conv/angle$0.002Developer Utilities
Angular acceleration converter
rad/s², deg/s² and rev/min², free
POST /conv/angular-acceleration$0.002Developer Utilities
Angular velocity converter
rad/s, deg/s, RPM, RPS free
POST /conv/angular-velocity$0.002Developer Utilities
Area converter
m², ft², acres, hectares, mi², km² free
POST /conv/area$0.002Developer Utilities
Astronomical distance converter
AU, ly, pc, km, mi, free
POST /conv/astronomical-distance$0.002Developer Utilities
Blood glucose converter
mg/dL ↔ mmol/L free
POST /conv/blood-glucose$0.002Developer Utilities
Bra size converter
US, UK, EU, French & Australian sizes, free
POST /conv/bra-size$0.002Developer Utilities
Capacitance converter
farads, millifarads, microfarads, picofarads, free
POST /conv/capacitance$0.002Developer Utilities
Catalytic activity converter
katal, µkat, nkat and enzyme units (U), free
POST /conv/catalytic-activity$0.002Developer Utilities
Cholesterol unit converter
mg/dL ↔ mmol/L for total, HDL and LDL, free
POST /conv/cholesterol$0.002Developer Utilities
Clothing size converter
US, UK, EU and S/M/L, free
POST /conv/clothing-size$0.002Developer Utilities
Molar concentration converter
mol/L, mmol/L, µmol/L, mol/m³ free
POST /conv/concentration$0.002Developer Utilities
Conductance converter
siemens, millisiemens, microsiemens, free
POST /conv/conductance$0.002Developer Utilities
Data transfer rate converter
bps, Mbps, MB/s, free
POST /conv/data-rate$0.002Developer Utilities
Digital storage converter
bytes, KB, MB, GB, TB, KiB, MiB free
POST /conv/data-size$0.002Developer Utilities
Density converter
kg/m³, g/cm³, lb/ft³ and lb/gal, free
POST /conv/density$0.002Developer Utilities
Dynamic viscosity converter
Pa·s, poise, cP, lbf·s/ft² free
POST /conv/dynamic-viscosity$0.002Developer Utilities
Electric charge converter
C, mC, µC, Ah, mAh, e free
POST /conv/electric-charge$0.002Developer Utilities
Electric current converter
A, mA, µA, kA, abA, free
POST /conv/electric-current$0.002Developer Utilities
Electric field strength converter
V/m, V/cm, kV/m, V/mil, free
POST /conv/electric-field$0.002Developer Utilities
Energy converter
joules, calories, kWh, BTU, eV, free
POST /conv/energy$0.002Developer Utilities
Fahrenheit to Celsius converter
exact (F−32)×5/9, free
POST /conv/fahrenheit-to-celsius$0.002Developer Utilities
Volume flow rate converter
L/s, m³/h, GPM, CFM, free
POST /conv/flow-rate$0.002Developer Utilities
Force converter
newtons, kN, dynes, lbf, kgf, poundals, free
POST /conv/force$0.002Developer Utilities
Frequency converter
Hz, kHz, MHz, GHz, RPM, rad/s free
POST /conv/frequency$0.002Developer Utilities
Frequency wavelength converter
f ↔ λ with c or custom speed, free
POST /conv/frequency-wavelength$0.002Developer Utilities
Fuel economy converter
MPG US, MPG imperial, km/L and L/100km, free
POST /conv/fuel-economy$0.002Developer Utilities
Fuel price unit converter
US gal, imperial gal, liter, free
POST /conv/fuel-price$0.002Developer Utilities
Grain weight converter
grains, grams, milligrams, ounces, free
POST /conv/grain-weight$0.002Developer Utilities
Hat size converter
US fitted, UK, EU cm, head circumference, free
POST /conv/hat-size$0.002Developer Utilities
Heat flux density converter
W/m², W/cm², BTU/(h·ft²), cal/(s·cm²), free
POST /conv/heat-flux$0.002Developer Utilities
Heat transfer coefficient converter
W/(m²·K), BTU/(h·ft²·°F), free
POST /conv/heat-transfer-coefficient$0.002Developer Utilities
Illuminance converter
lux, foot-candles, phot, lm/m² free
POST /conv/illuminance$0.002Developer Utilities
Inductance converter
H, mH, µH, nH, pH, free
POST /conv/inductance$0.002Developer Utilities
Gold karat converter
karats, fineness, purity %, free
POST /conv/karat-gold$0.002Developer Utilities
Kinematic viscosity converter
m²/s, stokes, centistokes and ft²/s, free
POST /conv/kinematic-viscosity$0.002Developer Utilities
Luminance converter
nit, stilb, lambert, foot-lambert and apostilb, free
POST /conv/luminance$0.002Developer Utilities
Luminous flux converter
lm, mlm, µlm, klm, Mlm, free
POST /conv/luminous-flux$0.002Developer Utilities
Luminous intensity converter
cd, mcd, kcd, candlepower, free
POST /conv/luminous-intensity$0.002Developer Utilities
Magnetic flux converter
weber, milliweber, microweber, maxwell, free
POST /conv/magnetic-flux$0.002Developer Utilities
Magnetic flux density converter
tesla, millitesla, gauss, Wb/m², free
POST /conv/magnetic-flux-density$0.002Developer Utilities
Mass converter
kg, g, lb, oz, stone, tonne and mg, free
POST /conv/mass$0.002Developer Utilities
Mass flow rate converter
kg/s, g/s, lb/h, t/h, free
POST /conv/mass-flow-rate$0.002Developer Utilities
Molar mass converter
g/mol, kg/mol, kg/kmol, free
POST /conv/molar-mass$0.002Developer Utilities
Momentum converter
kg·m/s, g·cm/s, lb·ft/s free
POST /conv/momentum$0.002Developer Utilities
Running pace converter
min/km, min/mile, km/h and mph, free
POST /conv/pace$0.002Developer Utilities
Paper size dimensions
ISO A B C, US Letter, Legal, Tabloid, free
POST /conv/paper-size$0.002Developer Utilities
Paper weight converter
gsm ↔ lb for text, bond, cover, index
POST /conv/paper-weight$0.002Developer Utilities
Power converter
W, kW, MW, hp, BTU/h, ft·lb/s free
POST /conv/power$0.002Developer Utilities
PPM percent converter
ppm, ppb, percent and per-mille free
POST /conv/ppm$0.002Developer Utilities
Radiation exposure converter
C/kg, roentgen, mR, free
POST /conv/radiation-exposure$0.002Developer Utilities
Radioactivity converter
Bq, Ci, Rd and SI multiples, free
POST /conv/radioactivity$0.002Developer Utilities
Electrical resistance converter
ohms, mΩ, kΩ, MΩ, GΩ free
POST /conv/resistance$0.002Developer Utilities
Electrical resistivity converter
Ω·m, Ω·cm, μΩ·cm, Ω·cmil/ft free
POST /conv/resistivity$0.002Developer Utilities
Ring size converter
US, UK, EU and diameter mm equivalents, free
POST /conv/ring-size$0.002Developer Utilities
Roof pitch converter
rise-in-12, degrees and percent slope, free
POST /conv/roof-pitch$0.002Developer Utilities
Shoe size converter
US, UK, EU and cm, men & women, free
POST /conv/shoe-size$0.002Developer Utilities
Slope grade converter
percent grade, degrees and rise-over-run, free
POST /conv/slope-grade$0.002Developer Utilities
Solid angle converter
steradians, deg², spat, sphere free
POST /conv/solid-angle$0.002Developer Utilities
Sound pressure level converter
Pa ↔ dB SPL, free
POST /conv/sound-level$0.002Developer Utilities
Specific energy converter
J/kg, kJ/kg, cal/g, BTU/lb, free
POST /conv/specific-energy$0.002Developer Utilities
Specific heat capacity converter
J/(kg·K), cal/(g·°C), BTU/(lb·°F), free
POST /conv/specific-heat$0.002Developer Utilities
Specific volume converter
m³/kg, L/kg, ft³/lb, free
POST /conv/specific-volume$0.002Developer Utilities
Speed converter
m/s, km/h, mph, knots, ft/s, free
POST /conv/speed$0.002Developer Utilities
Surface tension converter
N/m, mN/m, dyn/cm, lbf/ft, free
POST /conv/surface-tension$0.002Developer Utilities
Thermal conductivity converter
W/(m·K), BTU/(h·ft·°F), cal/(s·cm·°C) free
POST /conv/thermal-conductivity$0.002Developer Utilities
Thermal resistance converter
K/W, °C/W, °F·h/BTU, free
POST /conv/thermal-resistance$0.002Developer Utilities
Time unit converter
seconds, minutes, hours, days, weeks, ms and µs, free
POST /conv/time$0.002Developer Utilities
Torque converter
N·m, N·cm, lbf·ft, lbf·in, kgf·m, free
POST /conv/torque$0.002Developer Utilities
Screen size converter
diagonal in/cm and W×H from aspect ratio, free
POST /conv/tv-size$0.002Developer Utilities
Points to pixels converter
pt, px and picas at 96 DPI, free
POST /conv/typography-pt-px$0.002Developer Utilities
PX to EM converter
CSS pixels ↔ em with base font size, free
POST /conv/typography-px-em$0.002Developer Utilities
px to rem converter
CSS pixels ↔ rem with root font size
POST /conv/typography-px-rem$0.002Developer Utilities
Voltage converter
V, mV, µV, kV, MV, free
POST /conv/voltage$0.002Developer Utilities
Volume converter
liters, gallons, quarts, m³, ft³, free
POST /conv/volume$0.002Developer Utilities
Water hardness converter
ppm, mg/L, gpg, °dH free
POST /conv/water-hardness$0.002Developer Utilities
Wire gauge converter
AWG to mm, inches & area, free
POST /conv/wire-gauge$0.002Developer Utilities
Complete the square calculator
vertex form a(x−h)²+k, free
POST /algebra/complete-the-square$0.002Developer Utilities
Cross product calculator
3D vector a×b and parallelogram area, free
POST /algebra/cross-product$0.002Developer Utilities
Exponent rules calculator
product, quotient, power, free
POST /algebra/exponent-rules$0.002Developer Utilities
Linear inequality solver
ax+b ⊙ c for x, interval form, free
POST /algebra/inequality-solver$0.002Developer Utilities
Matrix inverse calculator
Gauss-Jordan A⁻¹, free
POST /algebra/matrix-inverse$0.002Developer Utilities
Matrix multiplication calculator
A×B product matrix, free
POST /algebra/matrix-multiply$0.002Developer Utilities
Polynomial long division calculator
quotient and remainder, free
POST /algebra/polynomial-divide$0.002Developer Utilities
Polynomial GCD calculator
Euclidean algorithm on coefficients, free
POST /algebra/polynomial-gcd$0.002Developer Utilities
Reduced row echelon form calculator
Gauss-Jordan RREF, free
POST /algebra/rref$0.002Developer Utilities
3×3 system of equations solver
Cramer's rule, free
POST /algebra/system-3x3$0.002Developer Utilities
Absolute magnitude calculator
M from m and distance (pc), free
POST /astro/absolute-magnitude$0.002Developer Utilities
Light travel time calculator
t = d/c from km or AU, free
POST /astro/light-travel-time$0.002Developer Utilities
Planet density calculator
mean bulk density from M and R, free
POST /astro/planet-density$0.002Developer Utilities
Schwarzschild radius calculator
Rs = 2GM/c² event horizon, free
POST /astro/schwarzschild-radius$0.002Developer Utilities
Surface gravity calculator
g = G·M/R² in m/s², free
POST /astro/surface-gravity$0.002Developer Utilities
Telescope resolution calculator
Rayleigh criterion θ=1.22λ/D, free
POST /astro/telescope-resolution$0.002Developer Utilities
Arrhenius equation calculator
k = A·e^(−Ea/RT), free
POST /chem/arrhenius$0.002Developer Utilities
Arrhenius temperature calculator
T from k, A, Ea, free
POST /chem/arrhenius-temperature$0.002Developer Utilities
Average molecular speed calculator
v̄ = √(8RT/πM), free
POST /chem/average-molecular-speed$0.002Developer Utilities
Average rate of reaction calculator
|Δc|/Δt from concentration, free
POST /chem/average-reaction-rate$0.002Developer Utilities
Avogadro's law moles calculator
n₂ = n₁(V₂/V₁), free
POST /chem/avogadro-law-moles$0.002Developer Utilities
Boiling point elevation calculator
ΔTb = i·Kb·m, free
POST /chem/boiling-point-elevation$0.002Developer Utilities
Born-Haber lattice energy calculator
U from formation, sublimation, free
POST /chem/born-haber-cycle$0.002Developer Utilities
Charles's law final volume calculator
V₂ = V₁(T₂/T₁), free
POST /chem/charles-final-volume$0.002Developer Utilities
Vaporization enthalpy calculator
Clausius–Clapeyron ΔHvap from two, free
POST /chem/clausius-clapeyron-enthalpy$0.002Developer Utilities
Combined gas law final volume calculator
V₂ = P₁V₁T₂/(P₂T₁), free
POST /chem/combined-gas-final-volume$0.002Developer Utilities
Cryoscopic constant calculator
Kf = ΔTf/(i·m), free
POST /chem/cryoscopic-constant$0.002Developer Utilities
Decay constant calculator
λ from half-life, free
POST /chem/decay-constant-half-life$0.002Developer Utilities
Degree of dissociation calculator
α from van't Hoff factor i, free
POST /chem/degree-dissociation-from-i$0.002Developer Utilities
Dilution factor calculator
DF = V_final/V_stock and fold dilution, free
POST /chem/dilution-factor$0.002Developer Utilities
Degree of dissociation calculator
α from Kc and initial, free
POST /chem/dissociation-from-kc$0.002Developer Utilities
Empirical formula from percent composition calculator
free
POST /chem/empirical-from-percent$0.002Developer Utilities
Heat of formation from reaction calculator
unknown ΔH_f, free
POST /chem/enthalpy-of-formation-unknown$0.002Developer Utilities
Molar enthalpy calculator
ΔH = Q/n from heat and moles, free
POST /chem/enthalpy-per-mole$0.002Developer Utilities
Equilibrium constant from Gibbs calculator
K = exp(−ΔG°/RT), free
POST /chem/equilibrium-from-gibbs$0.002Developer Utilities
Equilibrium yield calculator
percent of theoretical maximum at, free
POST /chem/equilibrium-yield$0.002Developer Utilities
Formula units calculator
N = (m/M)·N_A from mass, free
POST /chem/formula-units$0.002Developer Utilities
Fraction of molecules above Ea calculator
f = e^(−Ea/RT), free
POST /chem/fraction-molecules-above-ea$0.002Developer Utilities
Freezing point depression calculator
ΔTf = i·Kf·m from molality, free
POST /chem/freezing-point-depression-molality$0.002Developer Utilities
Fuel energy content calculator
E = m × energy density, free
POST /chem/fuel-energy-content$0.002Developer Utilities
Effusion remaining fraction calculator
lighter gas left after, free
POST /chem/gas-leak-effusion-fraction$0.002Developer Utilities
Gas stoichiometry volume calculator
product gas V from moles, free
POST /chem/gas-stoichiometry-volume$0.002Developer Utilities
Gas volume at STP calculator
V = n × 22.4 L, free
POST /chem/gas-stp-volume$0.002Developer Utilities
Gas temperature from P, V, n calculator
T = PV/nR (ideal gas), free
POST /chem/gas-temperature-from-ptv$0.002Developer Utilities
Gas volume at NTP calculator
V = n × 24.0 L, free
POST /chem/gas-volume-at-ntp$0.002Developer Utilities
Gibbs free energy calculator
ΔG = ΔH − TΔS from enthalpy, free
POST /chem/gibbs-from-enthalpy-entropy$0.002Developer Utilities
Grams of product from moles calculator
n×MM in grams, free
POST /chem/grams-of-product-from-moles$0.002Developer Utilities
Grams of solute for molarity calculator
M×V×MM in grams, free
POST /chem/grams-solute-for-molarity$0.002Developer Utilities
Instantaneous rate from tangent calculator
|Δc|/Δt from two nearby, free
POST /chem/instantaneous-rate$0.002Developer Utilities
Equilibrium constant at new temperature
van't Hoff K2 from K1, free
POST /chem/k-at-new-temperature$0.002Developer Utilities
Kp from partial pressures calculator
equilibrium Kp = ∏P^ν, free
POST /chem/kp-from-partial-pressures$0.002Developer Utilities
Ksp from solubility calculator
Ksp = ∏(νᵢ·s)^νᵢ from molar s, free
POST /chem/ksp-from-solubility$0.002Developer Utilities
Le Chatelier pressure shift calculator
equilibrium vs pressure, free
POST /chem/le-chatelier-pressure-shift$0.002Developer Utilities
Limiting reagent from masses calculator
two reactants, free
POST /chem/limiting-reactant-two$0.002Developer Utilities
Mass percent to molality calculator
w/w % + MM → mol/kg, free
POST /chem/mass-percent-to-molality$0.002Developer Utilities
Mass percent to ppm converter
% w/w → ppm & ppb, free
POST /chem/mass-percent-to-ppm$0.002Developer Utilities
Mass to gas volume calculator
V = mRT/(MP) ideal gas, free
POST /chem/mass-to-gas-volume$0.002Developer Utilities
Mass-to-mass stoichiometry calculator
product mass from reactant, free
POST /chem/mass-to-mass-stoich$0.002Developer Utilities
mg/L to molarity calculator
concentration + molar mass → mol/L, free
POST /chem/mg-per-liter-to-molarity$0.002Developer Utilities
Molar concentration calculator
c = n/V in mol/L, free
POST /chem/molar-concentration$0.002Developer Utilities
Molar mass from boiling point elevation
M = Kb·g / (ΔTb·kg), free
POST /chem/molar-mass-from-bp-elevation$0.002Developer Utilities
Molar mass from gas density calculator
M = ρRT/P (ideal gas), free
POST /chem/molar-mass-from-gas-density$0.002Developer Utilities
Molarity from moles and volume calculator
M = n/V in mol/L, free
POST /chem/molarity-from-moles-volume$0.002Developer Utilities
Molarity to molality calculator
M, density, MM → mol/kg, free
POST /chem/molarity-to-molality$0.002Developer Utilities
Mole fraction to mass percent calculator
free binary conversion
POST /chem/mole-fraction-to-mass-percent$0.002Developer Utilities
Osmolarity calculator
Osm = i·M in osmoles per liter, free
POST /chem/osmolarity$0.002Developer Utilities
Oxygen for combustion calculator
moles O₂ for CₓHᵧ hydrocarbon, free
POST /chem/oxygen-required-combustion$0.002Developer Utilities
Particles to moles calculator
n = N / N_A, free
POST /chem/particles-to-moles$0.002Developer Utilities
Percent composition calculator
mass % from formula, free
POST /chem/percent-composition$0.002Developer Utilities
Percent to molarity calculator
mass % + density → mol/L, free
POST /chem/percent-to-molarity$0.002Developer Utilities
Percent water in hydrate calculator
mass % H₂O from hydrate &, free
POST /chem/percent-water-in-hydrate$0.002Developer Utilities
Strong acid pH calculator
pH = −log₁₀(C) monoprotic, free
POST /chem/ph-strong-acid$0.002Developer Utilities
PPB concentration calculator
parts per billion by mass, free
POST /chem/ppb-concentration$0.002Developer Utilities
PPM from molarity calculator
M, molar mass, density → ppm, free
POST /chem/ppm-from-molarity$0.002Developer Utilities
Equilibrium direction predictor
Q vs K shift direction, free
POST /chem/q-vs-k-direction$0.002Developer Utilities
Rate constant from half-life calculator
k = ln(2)/t½, free
POST /chem/rate-constant-from-half-life$0.002Developer Utilities
Graham's law calculator
relative effusion rate √(M₂/M₁), free
POST /chem/rate-of-effusion$0.002Developer Utilities
Reaction order from rate data calculator
n = log(r₁/r₂)/log(c₁/c₂), free
POST /chem/reaction-order-from-rates$0.002Developer Utilities
Solution boiling point calculator
Tb = T0 + i·Kb·m, free
POST /chem/solution-boiling-point$0.002Developer Utilities
Specific heat from calorimetry calculator
c = Q/(m·ΔT), free
POST /chem/specific-heat-from-calorimetry$0.002Developer Utilities
Stock solution volume calculator
V1 from C1, C2, V2 dilution, free
POST /chem/stock-solution-volume$0.002Developer Utilities
Theoretical moles of product calculator
limiting moles × mole ratio, free
POST /chem/theoretical-moles-product$0.002Developer Utilities
Theoretical yield from limiting reactant calculator
moles, free
POST /chem/theoretical-yield-from-limiting$0.002Developer Utilities
Total ion concentration calculator
C = i·M from salt molarity, free
POST /chem/total-ion-concentration$0.002Developer Utilities
Total pressure of gas mixture calculator
Dalton P = ΣPᵢ, free
POST /chem/total-pressure-gas-mixture$0.002Developer Utilities
Van der Waals pressure calculator
P = nRT/(V−nb) − an²/V², free
POST /chem/van-der-waals-pressure$0.002Developer Utilities
Vapor pressure molar mass calculator
M from relative lowering, free
POST /chem/vapor-pressure-molar-mass$0.002Developer Utilities
Volume percent calculator
% v/v from solute and solution, free
POST /chem/volume-percent$0.002Developer Utilities
Volume-to-volume gas stoichiometry calculator
V₂ from V₁ and coeffs, free
POST /chem/volume-to-volume-gas-stoich$0.002Developer Utilities
Work of gas expansion calculator
W = −P_ext·ΔV, free
POST /chem/work-gas-expansion$0.002Developer Utilities
Zero-order half-life calculator
t½ = [A]₀/(2k), free
POST /chem/zero-order-half-life$0.002Developer Utilities
WCAG contrast ratio checker
AA/AAA for normal and large text
POST /color/contrast$0.002Developer Utilities
RGB to hex converter
0–255 channels to #RRGGBB, free
POST /color/rgb-hex$0.002Developer Utilities
RGB to HSV converter
0–255 channels to hue, saturation, value, free
POST /color/rgb-hsv$0.002Developer Utilities
RGB to LAB converter
sRGB channels to CIE L*a*b* (D65), free
POST /color/rgb-lab$0.002Developer Utilities
Color temperature to RGB
Kelvin 1000–40000 to sRGB, free
POST /color/temperature$0.002Developer Utilities
Tetradic color scheme generator
four hues from one hex, free
POST /color/tetradic$0.002Developer Utilities
Combinations with repetition
multiset C(n+r−1, r), free
POST /combo/combinations-with-repetition$0.002Developer Utilities
Handshake problem calculator
n choose 2 and inverse, free
POST /combo/handshake$0.002Developer Utilities
Monotone lattice paths on an a×b grid
C(a+b, a), free
POST /combo/lattice-paths$0.002Developer Utilities
Unsigned Stirling numbers of the first kind
c(n,k) cycles, free
POST /combo/stirling-first$0.002Developer Utilities
Butter measurement converter
sticks, tbsp, cups, grams free
POST /cook/butter$0.002Developer Utilities
Cake tin size converter
round ↔ square by area, in & cm free
POST /cook/cake-tin$0.002Developer Utilities
Honey cups to grams converter
tbsp & density free
POST /cook/honey$0.002Developer Utilities
Pints to liters converter
US & imperial pint free
POST /cook/pints-liters$0.002Developer Utilities
Teaspoons to ml converter
US & metric tsp free
POST /cook/tsp-ml$0.002Developer Utilities
Add months to a date
shift calendar date with month-end clamp, free
POST /date/add-months$0.002Developer Utilities
Birthstone by birth month
traditional and modern stones, free
POST /date/birthstone$0.002Developer Utilities
Chinese zodiac sign calculator
animal by year and lunar New Year, free
POST /date/chinese-zodiac$0.002Developer Utilities
Days between two dates
whole calendar day count, free
POST /date/days-between$0.002Developer Utilities
Days elapsed in the year
days since January 1, free
POST /date/days-elapsed-year$0.002Developer Utilities
Easter Sunday date calculator
Gregorian computus by year, free
POST /date/easter-sunday$0.002Developer Utilities
Julian Day to date converter
Gregorian calendar from JDN, free
POST /date/from-julian-day$0.002Developer Utilities
Golden number and epact calculator
ecclesiastical year numbers, free
POST /date/golden-number$0.002Developer Utilities
ISO week number calculator
week and week-year from any date, free
POST /date/iso-week-number$0.002Developer Utilities
ISO week to date converter
calendar date from week year, free
POST /date/iso-week-to-date$0.002Developer Utilities
First and last day of month
calendar start and end dates, free
POST /date/month-start-end$0.002Developer Utilities
Next leap year finder
next Gregorian leap year on or after a year, free
POST /date/next-leap-year$0.002Developer Utilities
Next occurrence of a weekday
next Monday/Friday date from any day, free
POST /date/next-weekday$0.002Developer Utilities
Subtract days from a date
earlier calendar date calculator, free
POST /date/subtract-days$0.002Developer Utilities
Antenna length calculator
quarter-wave and half-wave from frequency, free
POST /elec/antenna-length$0.002Developer Utilities
Battery runtime calculator
hours from Wh and load watts, free
POST /elec/battery-runtime-wh$0.002Developer Utilities
Capacitor energy calculator
E = ½CV² in joules, free
POST /elec/capacitor-energy$0.002Developer Utilities
Speaker crossover calculator
frequency from L and C, free
POST /elec/crossover-frequency$0.002Developer Utilities
dBm to dBW calculator
convert dBm to dBW, free
POST /elec/dbm-to-dbw$0.002Developer Utilities
dBm to watts calculator
convert dBm to W and mW, free
POST /elec/dbm-to-watts$0.002Developer Utilities
Electric potential calculator
V=kQ/r for a point charge, free
POST /elec/electric-potential$0.002Developer Utilities
EMF terminal voltage calculator
V = ε − Ir free
POST /elec/emf-internal-resistance$0.002Developer Utilities
Inductor energy calculator
E = ½LI² in joules, free
POST /elec/inductor-energy$0.002Developer Utilities
kWh calculator
energy from watts and running time, free
POST /elec/kwh-calculator$0.002Developer Utilities
Inverting amplifier calculator
op-amp gain Av = −Rf/Rin, free
POST /elec/op-amp-inverting$0.002Developer Utilities
Electrical power calculator
P=VI and P=I²R from any two values, free
POST /elec/power-vi$0.002Developer Utilities
Parallel resistance calculator
equivalent Req from R1∥R2∥…, free
POST /elec/resistors-parallel$0.002Developer Utilities
RLC resonant frequency calculator
f₀ and Q from L, C, R, free
POST /elec/rlc-resonance$0.002Developer Utilities
Smoothing capacitor calculator
C = I/(2f·Vr) filter size, free
POST /elec/smoothing-capacitor$0.002Developer Utilities
Solenoid magnetic field calculator
B = μ₀ n I, free
POST /elec/solenoid-field$0.002Developer Utilities
Baconian cipher encoder and decoder
five-letter A/B codes, free
POST /enc/bacon$0.002Developer Utilities
Base45 encoder and decoder
RFC 9285 for QR credentials, free
POST /enc/base45$0.002Developer Utilities
Base64url encoder and decoder
URL-safe, no padding, free
POST /enc/base64url$0.002Developer Utilities
Columnar transposition cipher
encrypt decrypt with keyword, free
POST /enc/columnar$0.002Developer Utilities
Text to ASCII codes converter
decimal char codes, free
POST /enc/decimal-ascii$0.002Developer Utilities
Four-square cipher encoder and decoder
two keywords, free
POST /enc/four-square$0.002Developer Utilities
HTML entities encoder and decoder
named and numeric, free
POST /enc/html-entities$0.002Developer Utilities
Morse code translator
encode and decode text free
POST /enc/morse$0.002Developer Utilities
Quoted-printable encoder and decoder
MIME QP encode/decode, free
POST /enc/quoted-printable$0.002Developer Utilities
ROT47 encoder and decoder
printable ASCII cipher, free
POST /enc/rot47$0.002Developer Utilities
Flag semaphore translator
encode and decode arm positions free
POST /enc/semaphore$0.002Developer Utilities
Trithemius cipher encoder and decoder
progressive shift, free
POST /enc/trithemius$0.002Developer Utilities
Vigenère cipher encoder and decoder
keyword polyalphabetic, free
POST /enc/vigenere$0.002Developer Utilities
Base36 encoder
convert integer to or from base-36 (0-9 A-Z), free
POST /fmt/base36$0.002Developer Utilities
BCD converter
decimal ↔ 8421 binary-coded decimal, free
POST /fmt/bcd$0.002Developer Utilities
Binary to decimal converter
base-2 to base-10, free
POST /fmt/binary-decimal$0.002Developer Utilities
Decimal to hex converter
base-10 integer to base-16, free
POST /fmt/decimal-hex$0.002Developer Utilities
Engineering notation converter
SI prefixes, free
POST /fmt/engineering-notation$0.002Developer Utilities
Greek numeral converter
Ionic numerals with keraia, free
POST /fmt/greek-numerals$0.002Developer Utilities
Percent to fraction converter
reduced fraction from %, free
POST /fmt/percent-fraction$0.002Developer Utilities
Roman fraction converter
uncia notation from twelfths, free
POST /fmt/roman-fraction$0.002Developer Utilities
Significant figures rounder
round to N sig figs, free
POST /fmt/sig-figs$0.002Developer Utilities
Along-track distance calculator
great-circle projection, free
POST /geo/along-track-distance$0.002Developer Utilities
Compass direction to bearing
32-point name to degrees, free
POST /geo/compass-to-bearing$0.002Developer Utilities
Geohash decoder
latitude, longitude & cell error, free
POST /geo/geohash-decode$0.002Developer Utilities
Great-circle path intersection
two bearings meet, free
POST /geo/great-circle-intersection$0.002Developer Utilities
Magnetic to true bearing
declination conversion both ways, free
POST /geo/magnetic-true-bearing$0.002Developer Utilities
Geographic polygon area
spherical m² from lat/lon ring, free
POST /geo/polygon-area$0.002Developer Utilities
Rhumb line distance calculator
constant-bearing path, free
POST /geo/rhumb-distance$0.002Developer Utilities
Map tile to lat/lon
slippy XYZ north-west corner, free
POST /geo/tile-to-latlon$0.002Developer Utilities
UTM to lat/lon converter
zone, easting, northing to WGS84, free
POST /geo/utm-to-latlon$0.002Developer Utilities
Web Mercator projection calculator
lat/lon to EPSG:3857 X/Y meters, free
POST /geo/web-mercator-project$0.002Developer Utilities
Chord length calculator
from radius and angle or distance to center
POST /geom/chord-length$0.002Developer Utilities
Circle through three points
find center and radius from three coordinates
POST /geom/circle-from-3-points$0.002Developer Utilities
Cone volume calculator
volume, slant height, lateral and total surface
POST /geom/cone$0.002Developer Utilities
Dodecahedron calculator
volume and surface area from edge length
POST /geom/dodecahedron$0.002Developer Utilities
Ellipse calculator
area, Ramanujan perimeter, eccentricity, foci
POST /geom/ellipse$0.002Developer Utilities
Line intersection calculator
two lines in slope-intercept or standard
POST /geom/line-intersection$0.002Developer Utilities
Pipe volume calculator
internal and material volume from inner and outer
POST /geom/pipe-volume$0.002Developer Utilities
Polygon area calculator
shoelace formula from ordered vertices
POST /geom/polygon-area-shoelace$0.002Developer Utilities
Prism surface area calculator
lateral and total area from perimeter
POST /geom/prism-surface$0.002Developer Utilities
Pyramid volume calculator
volume, slant height and surface area
POST /geom/pyramid$0.002Developer Utilities
Rhombus calculator
area, perimeter, and side from diagonals or angle
POST /geom/rhombus$0.002Developer Utilities
Slope calculator
line slope and inclination angle from two points
POST /geom/slope$0.002Developer Utilities
Spherical segment calculator
volume and lateral zone area from radius
POST /geom/spherical-segment$0.002Developer Utilities
Square pyramid volume
slant height, lateral and total surface area
POST /geom/square-pyramid-solver$0.002Developer Utilities
Torus volume calculator
volume and surface area from tube and center
POST /geom/torus$0.002Developer Utilities
45-45-90 triangle calculator
legs, hypotenuse, and area from one side
POST /geom/triangle-45-45-90$0.002Developer Utilities
Circumcenter calculator
center and radius of a triangle's circumcircle
POST /geom/triangle-circumcenter$0.002Developer Utilities
SSA triangle calculator
ambiguous case, zero one or two solutions
POST /geom/triangle-ssa$0.002Developer Utilities
Calorie deficit calculator
daily intake from weight-loss goal, free
POST /health/calorie-deficit$0.002Developer Utilities
Cycling speed from power calculator
watts, weight, grade & CdA, free
POST /health/cycling-speed-power$0.002Developer Utilities
Body frame size calculator
small, medium or large from height &, free
POST /health/frame-size$0.002Developer Utilities
Lean body mass calculator
Boer formula from weight, height & sex, free
POST /health/lean-body-mass$0.002Developer Utilities
Maximum heart rate calculator
Fox, Tanaka, Gulati formulas free
POST /health/max-heart-rate$0.002Developer Utilities
Pace to speed converter
min/km or min/mi to km/h and mph, free
POST /health/pace-to-speed$0.002Developer Utilities
Pulse pressure calculator
systolic minus diastolic, free
POST /health/pulse-pressure$0.002Developer Utilities
Swimming calorie calculator
calories burned by duration, weight
POST /health/swimming-calories$0.002Developer Utilities
Rockport one-mile walk VO2 max calculator
free estimate
POST /health/vo2max-rockport$0.002Developer Utilities
Walking calorie calculator
calories burned from distance, pace, weight
POST /health/walking-calories$0.002Developer Utilities
Guitar capo key calculator
sounding key and chords from shapes and fret
POST /hobby/capo-key$0.002Developer Utilities
Crochet yarn estimator
length from dimensions, gauge and yardage
POST /hobby/crochet-yarn$0.002Developer Utilities
Dice probability calculator
exact P(sum) for n dice, free
POST /hobby/dice-probability$0.002Developer Utilities
Flash guide number calculator
aperture or distance from GN and ISO
POST /hobby/flash-guide-number$0.002Developer Utilities
Frequency to note calculator
nearest note, octave and cents from Hz
POST /hobby/frequency-to-note$0.002Developer Utilities
Hyperfocal distance calculator
H and near limit from f, N, CoC
POST /hobby/hyperfocal$0.002Developer Utilities
Line height calculator
px from font size and ratio, free
POST /hobby/line-height$0.002Developer Utilities
500 rule calculator
max shutter before star trails (focal × crop)
POST /hobby/rule-500$0.002Developer Utilities
Baseboard trim calculator
pieces from room perimeter and door, free
POST /home/baseboard$0.002Developer Utilities
Brick calculator
bricks needed from wall area, free
POST /home/bricks$0.002Developer Utilities
Drywall sheet calculator
sheets and screws from wall and ceiling, free
POST /home/drywall$0.002Developer Utilities
Fence picket calculator
pickets from length, width and gap, free
POST /home/fence-pickets$0.002Developer Utilities
Grass seed calculator
seed amount from lawn area and rate, free
POST /home/grass-seed$0.002Developer Utilities
Mulch calculator
cubic yards and bags from bed area and depth, free
POST /home/mulch$0.002Developer Utilities
Paint quantity calculator
liters from wall area or room size, free
POST /home/paint-needed$0.002Developer Utilities
Rafter length calculator
common rafter from span, free
POST /home/rafter-length$0.002Developer Utilities
Retaining wall block calculator
blocks and courses from length, free
POST /home/retaining-wall-blocks$0.002Developer Utilities
Tile grout calculator
kg from tile size, joint width and area, free
POST /home/tile-grout$0.002Developer Utilities
Room wall area calculator
net paintable walls from L×W×H, free
POST /home/wall-area$0.002Developer Utilities
Cost per day calculator
annual price to daily, weekly, monthly, free
POST /life/cost-per-day$0.002Developer Utilities
Cost per use calculator
price divided by expected uses, free
POST /life/cost-per-use$0.002Developer Utilities
Emergency fund calculator
months of essential expenses, free
POST /life/emergency-fund$0.002Developer Utilities
Hourly to salary converter
annual pay from wage, hours, weeks free
POST /life/hourly-to-salary$0.002Developer Utilities
Reverse sales tax calculator
pre-tax price from tax-inclusive total, free
POST /life/reverse-sales-tax$0.002Developer Utilities
Rule of 72 calculator
years to double at a growth rate, free
POST /life/rule-of-72$0.002Developer Utilities
Geometric sequence calculator
n-th term and finite sum, free
POST /math/geometric-sequence$0.002Developer Utilities
Pell number calculator
P_n = 2P_{n-1}+P_{n-2}, free bigint
POST /math/pell-number$0.002Developer Utilities
Perfect square checker
n-th square and isqrt test, free
POST /math/square-number$0.002Developer Utilities
Sum of first n cubes
1³+…+n³ = (n(n+1)/2)², free
POST /math/sum-of-cubes$0.002Developer Utilities
Superfactorial calculator
product of first n factorials, free bigint
POST /math/superfactorial$0.002Developer Utilities
Telescoping series sum
Σ 1/(k(k+1)) = n/(n+1), free
POST /math/telescoping-sum$0.002Developer Utilities
Tetrahedral number calculator
n-th Te_n = n(n+1)(n+2)/6, free
POST /math/tetrahedral-number$0.002Developer Utilities
Acceleration calculator
a = Δv/t average acceleration, free
POST /mech/acceleration$0.002Developer Utilities
Circular motion velocity calculator
v = 2πr/T tangential speed, free
POST /mech/circular-velocity$0.002Developer Utilities
Free fall time calculator
t = √(2d/g) from rest, free
POST /mech/free-fall-time$0.002Developer Utilities
Friction force calculator
F = μ·N from coefficient and normal force, free
POST /mech/friction-force$0.002Developer Utilities
Inelastic collision calculator
common final velocity v_f, free
POST /mech/inelastic-collision$0.002Developer Utilities
Lever calculator
effort force for a balanced lever, free
POST /mech/lever$0.002Developer Utilities
Gravitational potential energy calculator
PE = m·g·h in joules, free
POST /mech/potential-energy$0.002Developer Utilities
Projectile max height calculator
H = v₀² sin²θ / (2g), free
POST /mech/projectile-max-height$0.002Developer Utilities
RPM to linear speed calculator
v = 2πr·(rpm/60) rim speed, free
POST /mech/rpm-to-linear$0.002Developer Utilities
Spring potential energy calculator
PE = ½kx² in joules, free
POST /mech/spring-potential-energy$0.002Developer Utilities
Velocity components calculator
horizontal vx and vertical vy, free
POST /mech/velocity-components$0.002Developer Utilities
Weight calculator
W = m·g force in newtons, free
POST /mech/weight-force$0.002Developer Utilities
Abundant number checker
aliquot sum and abundance amount, free
POST /numth/abundant-number$0.002Developer Utilities
Carmichael function calculator
compute λ(n) for any positive integer
POST /numth/carmichael-function$0.002Developer Utilities
Chinese remainder theorem solver
solve x ≡ ai mod ni, free
POST /numth/chinese-remainder$0.002Developer Utilities
Collatz conjecture calculator
3n+1 sequence, steps and peak, free
POST /numth/collatz$0.002Developer Utilities
Coprime checker
test gcd(a,b)=1 and return the gcd, free
POST /numth/coprime-checker$0.002Developer Utilities
Kaprekar number checker
square splits that add back to n, free
POST /numth/kaprekar-number$0.002Developer Utilities
Nth prime calculator
find the n-th prime number, free
POST /numth/nth-prime$0.002Developer Utilities
Prime factorization calculator
factor any integer into prime powers
POST /numth/prime-factorization$0.002Developer Utilities
Primitive root calculator
smallest generator mod prime p, free
POST /numth/primitive-root$0.002Developer Utilities
Smith number checker
digit sum vs prime-factor digit sum, free
POST /numth/smith-number$0.002Developer Utilities
Double slit calculator
fringe spacing Δy = λL/d, free
POST /optics/double-slit$0.002Developer Utilities
Focal length calculator
lens f from object & image distance, free
POST /optics/focal-length$0.002Developer Utilities
Refractive index calculator
n = c/v or speed from n, free
POST /optics/refractive-index$0.002Developer Utilities
Thin lens calculator
image distance & magnification, free
POST /optics/thin-lens$0.002Developer Utilities
Sound level distance calculator
inverse-square dB from one range, free
POST /phys/decibel-distance$0.002Developer Utilities
Frequency calculator
f = v / λ from wave speed and wavelength, free
POST /phys/frequency$0.002Developer Utilities
String harmonic frequency calculator
f₁ = (1/2L)√(T/μ), free
POST /phys/harmonic-string$0.002Developer Utilities
Bayes theorem calculator
posterior from prior, sensitivity, FPR, free
POST /prob/bayes-theorem$0.002Developer Utilities
Binomial probability calculator
P(X=k), CDF, mean, variance, free
POST /prob/binomial-distribution$0.002Developer Utilities
Lottery odds calculator
match m of r in n-choose-r, optional bonus, free
POST /prob/lottery-odds$0.002Developer Utilities
Negative binomial calculator
P(r-th success on trial k), free
POST /prob/negative-binomial$0.002Developer Utilities
Factor of safety calculator
n = ultimate strength / working stress, free
POST /sci/factor-of-safety$0.002Developer Utilities
Poisson's ratio calculator
ν = −ε_lateral/ε_axial from strains, free
POST /sci/poisson-ratio$0.002Developer Utilities
Engineering strain calculator
ε = ΔL/L₀ as ratio and percent, free
POST /sci/strain$0.002Developer Utilities
Correlation coefficient calculator
Pearson r for two series, free
POST /stat/correlation$0.002Developer Utilities
Mean absolute deviation calculator
MAD about the mean, free
POST /stat/mean-absolute-deviation$0.002Developer Utilities
Percentile calculator
k-th percentile & rank by linear, free
POST /stat/percentile$0.002Developer Utilities
Standard deviation calculator
population & sample σ, variance, free
POST /stat/standard-deviation$0.002Developer Utilities
Convert to alternating case
aLtErNaTiNg text converter, free
POST /str/alternating-case$0.002Developer Utilities
Convert to camelCase
phrase to camelCase converter, free
POST /str/camel-case$0.002Developer Utilities
Count characters
with/without spaces and UTF-8 bytes, free
POST /str/char-count$0.002Developer Utilities
Convert to CONSTANT_CASE
phrase to SCREAMING_SNAKE_CASE, free
POST /str/constant-case$0.002Developer Utilities
Count vowels and consonants
digits and other chars too, free
POST /str/count-vowels$0.002Developer Utilities
Word frequency counter
count and rank words in text, free
POST /str/frequency$0.002Developer Utilities
Remove all whitespace
strip spaces, tabs, line breaks free
POST /str/remove-whitespace$0.002Developer Utilities
Repeat text
string repeater with optional separator, free
POST /str/repeat$0.002Developer Utilities
Text to slug
URL-friendly titles with hyphens, free
POST /str/slugify$0.002Developer Utilities
Convert to uppercase
all-caps text converter, free
POST /str/uppercase$0.002Developer Utilities
Boiling point altitude calculator
water Tb vs elevation or pressure, free
POST /thermo/boiling-point-altitude$0.002Developer Utilities
Combined gas law calculator
P₁V₁/T₁ = P₂V₂/T₂, free
POST /thermo/combined-gas-law$0.002Developer Utilities
Coefficient of performance calculator
COP = Q/W refrigerator &, free
POST /thermo/cop-refrigerator$0.002Developer Utilities
Volumetric flow rate calculator
Q = A·v pipe discharge, free
POST /thermo/flow-rate$0.002Developer Utilities
Carnot efficiency calculator
η = 1 − Tc/Th heat engine limit, free
POST /thermo/heat-engine-efficiency$0.002Developer Utilities
Latent heat calculator
Q = mL phase-change energy, free
POST /thermo/latent-heat$0.002Developer Utilities
Poiseuille flow calculator
Q = π r⁴ ΔP / (8 μ L), free
POST /thermo/poiseuille-flow$0.002Developer Utilities
Stefan-Boltzmann calculator
P = εσAT⁴ radiated power, free
POST /thermo/stefan-boltzmann$0.002Developer Utilities
Volumetric expansion calculator
ΔV = V₀βΔT thermal volume change, free
POST /thermo/volumetric-expansion$0.002Developer Utilities
Carry-on size checker
does your bag fit airline limits, free
POST /travel/carry-on-check$0.002Developer Utilities
EV range calculator
km or miles from battery kWh and efficiency, free
POST /travel/ev-range$0.002Developer Utilities
Jet lag recovery calculator
days to adjust by time zones, free
POST /travel/jet-lag-recovery$0.002Developer Utilities
Layover connection time checker
length vs minimum MCT, free
POST /travel/layover-time$0.002Developer Utilities
Trip fuel volume calculator
liters or gallons from distance and MPG, free
POST /travel/trip-fuel-volume$0.002Developer Utilities
Trip total cost calculator
fuel, tolls, lodging and food budget, free
POST /travel/trip-total-cost$0.002Developer Utilities
Degrees to radians converter
and back, free online
POST /trig/deg-to-rad$0.002Developer Utilities
Hypotenuse calculator
find c or a missing leg free online
POST /trig/hypotenuse$0.002Developer Utilities
Arcsine calculator
asin in degrees and radians, free
POST /trig/inverse-sin$0.002Developer Utilities
Trig identity verifier
Pythagorean and quotient residuals, free
POST /trig/pythagorean-identity$0.002Developer Utilities
Secant, cosecant & cotangent calculator
free online
POST /trig/secant-cosecant$0.002Developer Utilities
Unit circle calculator
cos, sin, and radians, free online
POST /trig/unit-circle$0.002Developer Utilities
Binomial expansion calculator
expand (a+b)^n, free
POST /algebra/binomial-expansion$0.002Developer Utilities
Cramer's rule calculator
solve Ax=b with determinants, free
POST /algebra/cramers-rule$0.002Developer Utilities
Cubic equation solver
all three roots of ax³+bx²+cx+d=0 via Cardano, free
POST /algebra/cubic-equation$0.002Developer Utilities
Discriminant calculator
b² − 4ac and root type, free
POST /algebra/discriminant$0.002Developer Utilities
Dot product calculator
vectors, angle, free online
POST /algebra/dot-product$0.002Developer Utilities
2×2 eigenvalue calculator
characteristic equation, free
POST /algebra/eigenvalues-2x2$0.002Developer Utilities
Exponential equation solver
solve b^x = y for x with logs, free
POST /algebra/exponential-equation$0.002Developer Utilities
Factor quadratic calculator
ax²+bx+c into binomials over rationals, free
POST /algebra/factor-quadratic$0.002Developer Utilities
Gaussian elimination solver
solve Ax = b with back-substitution, free
POST /algebra/gaussian-elimination$0.002Developer Utilities
Linear equation solver
solve ax + b = c for x, free
POST /algebra/linear-equation$0.002Developer Utilities
Logarithm expand & condense
product, quotient, power laws, free
POST /algebra/log-expand$0.002Developer Utilities
Logarithm calculator
log base b of x, ln and log10, free
POST /algebra/logarithm$0.002Developer Utilities
Matrix addition & subtraction
entrywise, free online
POST /algebra/matrix-add$0.002Developer Utilities
Matrix determinant calculator
det(A) via cofactor expansion or LU, free
POST /algebra/matrix-determinant$0.002Developer Utilities
Matrix rank calculator
row echelon form and pivots, free
POST /algebra/matrix-rank$0.002Developer Utilities
Matrix trace calculator
sum of main diagonal entries of a square matrix, free
POST /algebra/matrix-trace$0.002Developer Utilities
Matrix transpose calculator
swap rows and columns, free online
POST /algebra/matrix-transpose$0.002Developer Utilities
Partial fraction decomposition
proper rational with linear & quadratic factors, free
POST /algebra/partial-fractions$0.002Developer Utilities
Polynomial addition calculator
add or subtract coefficient lists, simplified result, free
POST /algebra/polynomial-add$0.002Developer Utilities
Polynomial multiplication calculator
multiply two coefficient lists, free
POST /algebra/polynomial-multiply$0.002Developer Utilities
Polynomial root finder
all real roots from coefficients, free
POST /algebra/polynomial-roots$0.002Developer Utilities
Quadratic formula solver
roots, discriminant and vertex of ax²+bx+c=0, free
POST /algebra/quadratic-formula$0.002Developer Utilities
Rational root theorem
list candidate roots p/q, free
POST /algebra/rational-root$0.002Developer Utilities
Remainder theorem calculator
evaluate p(r) by Horner, free
POST /algebra/remainder-theorem$0.002Developer Utilities
Synthetic division calculator
divide by x − r, free
POST /algebra/synthetic-division$0.002Developer Utilities
Solve a 2×2 system of linear equations
Cramer's rule, free
POST /algebra/system-2x2$0.002Developer Utilities
Vector magnitude calculator
Euclidean norm and unit vector, free
POST /algebra/vector-magnitude$0.002Developer Utilities
Vector projection calculator
scalar & vector proj, free
POST /algebra/vector-projection$0.002Developer Utilities
Vieta's formulas calculator
sum and product of polynomial roots from coefficients, free
POST /algebra/vieta-formulas$0.002Developer Utilities
Angular size calculator
diameter in degrees & arcmin, free
POST /astro/angular-size$0.002Developer Utilities
Apoapsis and periapsis calculator
from semi-major axis and eccentricity, free
POST /astro/apoapsis-periapsis$0.002Developer Utilities
Apparent brightness calculator
L/(4πd²) inverse square, free
POST /astro/apparent-brightness$0.002Developer Utilities
Planet escape velocity calculator
v = √(2GM/r), free
POST /astro/body-escape-velocity$0.002Developer Utilities
Distance modulus calculator
parsecs & light-years, free
POST /astro/distance-modulus$0.002Developer Utilities
Geostationary orbit calculator
altitude from mass and rotation period, free
POST /astro/geostationary-orbit$0.002Developer Utilities
Gravitational force calculator
Newton's law F=Gm₁m₂/r² free
POST /astro/gravitational-force$0.002Developer Utilities
Hubble law calculator
galaxy distance from recession velocity and H0, free
POST /astro/hubble-distance$0.002Developer Utilities
Light-year converter
km, parsecs and AU, free
POST /astro/light-year-distance$0.002Developer Utilities
Orbital energy calculator
potential and total energy from mass and radius, free
POST /astro/orbital-energy$0.002Developer Utilities
Orbital period calculator
Kepler T from semi-major axis and mass, free
POST /astro/orbital-period$0.002Developer Utilities
Orbital velocity calculator
circular speed from mass and radius, free
POST /astro/orbital-velocity$0.002Developer Utilities
Stellar parallax calculator
star distance from parallax angle in parsecs and light-years, free
POST /astro/parallax-distance$0.002Developer Utilities
Redshift calculator
z and recession velocity from wavelengths, free
POST /astro/redshift-velocity$0.002Developer Utilities
Roche limit calculator
tidal breakup distance from densities and radius, free
POST /astro/roche-limit$0.002Developer Utilities
Synodic period calculator
from two orbital periods, free
POST /astro/synodic-period$0.002Developer Utilities
Rocket equation calculator
Δv = ve·ln(m₀/m_f), free
POST /astro/tsiolkovsky-rocket$0.002Developer Utilities
Weight on other planets calculator
Earth weight to Mercury Mars Jupiter free
POST /astro/weight-on-planet$0.002Developer Utilities
Actual yield calculator
from theoretical yield and percent yield, free
POST /chem/actual-yield-from-percent$0.002Developer Utilities
Activation energy calculator
Ea from two rate constants, free
POST /chem/arrhenius-activation-energy$0.002Developer Utilities
Arrhenius pre-exponential factor calculator
A from k, Ea, T, free
POST /chem/arrhenius-prefactor$0.002Developer Utilities
Atom economy calculator
green chemistry AE free
POST /chem/atom-economy$0.002Developer Utilities
Atoms to moles of compound calculator
n = N/(k·N_A), free
POST /chem/atoms-to-moles-of-compound$0.002Developer Utilities
Average atomic mass calculator
from isotope masses and abundances
POST /chem/average-atomic-mass$0.002Developer Utilities
Average kinetic energy of gas calculator
(3/2)kT per molecule, free
POST /chem/average-kinetic-energy-gas$0.002Developer Utilities
Avogadro's law calculator
final gas volume from moles, free
POST /chem/avogadro-law$0.002Developer Utilities
Moles to atoms calculator
Avogadro's number N = n·N_A, free
POST /chem/avogadro-number$0.002Developer Utilities
Bomb calorimeter calculator
molar heat of combustion from C, ΔT, n
POST /chem/bomb-calorimetry$0.002Developer Utilities
Bond energy reaction enthalpy calculator
ΔH from bonds
POST /chem/bond-enthalpy-reaction$0.002Developer Utilities
Boyle's law calculator
final gas pressure from volume, free
POST /chem/boyle-final-pressure$0.002Developer Utilities
Boyle's law final volume calculator
V2 from P1, V1, P2 at constant T, free
POST /chem/boyle-final-volume$0.002Developer Utilities
Buffer capacity calculator
β from acid and conjugate base, free
POST /chem/buffer-capacity$0.002Developer Utilities
Buffer pOH calculator
pOH from pKb and concentrations, free
POST /chem/buffer-poh$0.002Developer Utilities
C1V1 = C2V2 calculator
solve dilution for concentration or volume, free
POST /chem/c1v1-c2v2$0.002Developer Utilities
Calorimeter constant calculator
C = q/ΔT from heat and temperature change
POST /chem/calorimeter-constant$0.002Developer Utilities
Calorimetry heat released calculator
Q = m·c·ΔT from mass, specific heat and ΔT, free
POST /chem/calorimetry-heat$0.002Developer Utilities
Catalyst rate enhancement calculator
k_cat/k_uncat from Ea, free
POST /chem/catalyst-rate-enhancement$0.002Developer Utilities
Cell potential from Gibbs free energy
E° = −ΔG°/(nF)
POST /chem/cell-potential-from-gibbs$0.002Developer Utilities
Charles law final temperature calculator
T2 from V1, T1, V2 free
POST /chem/charles-final-temperature$0.002Developer Utilities
Clausius–Clapeyron calculator
T2 from two vapor pressures, free
POST /chem/clausius-clapeyron$0.002Developer Utilities
Colligative particle concentration calculator
M×i effective particles, free
POST /chem/colligative-particle-count$0.002Developer Utilities
Collision theory rate calculator
k = p·Z·e^(−Ea/RT), free
POST /chem/collision-frequency-factor$0.002Developer Utilities
Combined equilibrium constant calculator
overall K from steps, free
POST /chem/combined-equilibrium-constant$0.002Developer Utilities
Combined gas law final pressure calculator
P2 from V2, T2 free
POST /chem/combined-gas-final-pressure$0.002Developer Utilities
Combustion analysis calculator
empirical formula from CO2 and H2O, free
POST /chem/combustion-analysis$0.002Developer Utilities
Common ion effect solubility calculator
reduced molar solubility from Ksp, free
POST /chem/common-ion-solubility$0.002Developer Utilities
Gas compressibility factor calculator
Z = PVm/RT for real gases, free
POST /chem/compressibility-factor$0.002Developer Utilities
Concentration after evaporation calculator
concentrated solution from volume lost, free
POST /chem/concentration-after-evaporation$0.002Developer Utilities
Conjugate base to acid ratio calculator
[A−]/[HA] from pH and pKa, free
POST /chem/conjugate-ratio$0.002Developer Utilities
Faraday corrosion rate calculator
penetration rate from i_corr, free
POST /chem/corrosion-rate-faraday$0.002Developer Utilities
Van der Waals critical constants calculator
Tc, Pc, Vc from a and b, free
POST /chem/critical-constants$0.002Developer Utilities
Partial pressures from mole amounts
Dalton Pi=(ni/n)·P, free
POST /chem/dalton-from-moles$0.002Developer Utilities
Gas mole fraction from partial pressure
Dalton yi=Pi/P, free
POST /chem/dalton-mole-fraction$0.002Developer Utilities
Degree of dissociation calculator
α from C₀ and Ceq, free
POST /chem/degree-of-dissociation$0.002Developer Utilities
Density calculator
ρ=m/V from mass and volume, free
POST /chem/density-mass-volume$0.002Developer Utilities
Dilution calculator
solve M1V1=M2V2 for concentration or volume
POST /chem/dilution$0.002Developer Utilities
Dilution factor calculator
DF and fold dilution from volumes
POST /chem/dilution-factor-from-volumes$0.002Developer Utilities
pH after dilution calculator
strong acid pH from volumes, free
POST /chem/dilution-ph-strong-acid$0.002Developer Utilities
Dilution to target ppm calculator
stock volume for a final ppm
POST /chem/dilution-to-target-ppm$0.002Developer Utilities
Dilution water to add calculator
volume from C1 V1 C2 free
POST /chem/dilution-water-added$0.002Developer Utilities
Ebullioscopic constant calculator
Kb from ΔTb, molality and van't Hoff factor
POST /chem/ebullioscopic-constant$0.002Developer Utilities
Electrode potential vs pH calculator
hydrogen electrode Nernst, free
POST /chem/electrode-potential-ph$0.002Developer Utilities
Electrolysis time calculator
time to deposit mass from I, m, M, n, free
POST /chem/electrolysis-time$0.002Developer Utilities
Electron configuration calculator
ground-state config and valence electrons from atomic number, free
POST /chem/electron-configuration$0.002Developer Utilities
Electrorefining efficiency calculator
current efficiency from actual vs theoretical mass, free
POST /chem/electrorefining-efficiency$0.002Developer Utilities
Empirical formula calculator
from mass or percent composition
POST /chem/empirical-formula$0.002Developer Utilities
Empirical formula from masses calculator
ratio from mass and atomic mass
POST /chem/empirical-from-masses$0.002Developer Utilities
Reaction heat for amount calculator
Q = n·ΔH from moles and molar enthalpy, free
POST /chem/enthalpy-amount-scaling$0.002Developer Utilities
Enthalpy scaled by coefficients calculator
ΔH × factor for thermochemical equations, free
POST /chem/enthalpy-coefficient-scaling$0.002Developer Utilities
Heat of combustion per gram calculator
energy from molar ΔH and molar mass
POST /chem/enthalpy-combustion-per-gram$0.002Developer Utilities
Enthalpy of dilution calculator
molar ΔH_dil = q/n from heat and moles, free
POST /chem/enthalpy-dilution$0.002Developer Utilities
Enthalpy from heats of formation calculator
ΔH°_rxn free
POST /chem/enthalpy-from-formation$0.002Developer Utilities
Enthalpy from internal energy calculator
ΔH = ΔU + Δn_g RT
POST /chem/enthalpy-from-internal-energy$0.002Developer Utilities
Enthalpy of fusion calculator
ΔH_fus from heat and moles
POST /chem/enthalpy-of-fusion-moles$0.002Developer Utilities
Enthalpy of vaporization calculator
molar ΔH_vap = q/n from heat and moles, free
POST /chem/enthalpy-of-vaporization-moles$0.002Developer Utilities
Enthalpy of reaction calculator
ΔH from formation enthalpies
POST /chem/enthalpy-reaction$0.002Developer Utilities
Reaction entropy change calculator
ΔS from standard molar entropies
POST /chem/entropy-of-reaction$0.002Developer Utilities
Equilibrium constant calculator
Kc from concentrations, free
POST /chem/equilibrium-constant$0.002Developer Utilities
Equilibrium constant from cell potential
K from E°, n, T, free
POST /chem/equilibrium-constant-from-emf$0.002Developer Utilities
Equilibrium partial pressure from Kp calculator
gas stoichiometry, free
POST /chem/equilibrium-partial-pressure$0.002Developer Utilities
Equivalent weight calculator
EW = M / n from molar mass and valence, free
POST /chem/equivalent-weight$0.002Developer Utilities
Excess reactant remaining calculator
leftover mass free
POST /chem/excess-reactant-remaining$0.002Developer Utilities
Faraday electrolysis mass calculator
mass deposited from I, t, M, n, free
POST /chem/faraday-mass-deposited$0.002Developer Utilities
Final temperature of mixture calculator
two substances, free
POST /chem/final-temperature-two-substances$0.002Developer Utilities
First-order half-life calculator
t½ from rate constant k, free
POST /chem/first-order-half-life$0.002Developer Utilities
Formal charge calculator
valence, lone pairs, bonding electrons, free
POST /chem/formal-charge$0.002Developer Utilities
Fraction dissociated calculator
α from Ka and concentration, free
POST /chem/fraction-dissociated-from-ka$0.002Developer Utilities
Freezing mixture temperature calculator
ice-salt ΔTf from molality, free
POST /chem/freezing-mixture-temperature$0.002Developer Utilities
Freezing point depression calculator
ΔTf = i·Kf·m free
POST /chem/freezing-point-depression$0.002Developer Utilities
Gas collected over water calculator
dry gas partial pressure free
POST /chem/gas-collected-over-water$0.002Developer Utilities
Gas density at STP calculator
ρ from molar mass at 0 °C, 1 atm, free
POST /chem/gas-density-at-stp$0.002Developer Utilities
Ideal gas density calculator
ρ=PM/RT from P, M and T, free
POST /chem/gas-density-ideal$0.002Developer Utilities
Gas moles calculator
ideal gas n = PV/RT from pressure, volume and temperature, free
POST /chem/gas-moles-from-ptv$0.002Developer Utilities
Gas pressure from moles calculator
ideal-gas P=nRT/V, free
POST /chem/gas-pressure-from-moles$0.002Developer Utilities
Electrolysis gas volume calculator
Faraday charge to STP volume, free
POST /chem/gas-volume-electrolysis$0.002Developer Utilities
Gas volume from moles calculator
V = nRT/P ideal gas, free
POST /chem/gas-volume-from-moles$0.002Developer Utilities
Gay-Lussac final pressure calculator
P2 from P1, T1, T2 at constant V, free
POST /chem/gay-lussac-final-pressure$0.002Developer Utilities
Gay-Lussac's law calculator
final gas temperature from pressure, free
POST /chem/gay-lussac-final-temperature$0.002Developer Utilities
Spontaneity crossover temperature
T where ΔG = 0 from ΔH and ΔS
POST /chem/gibbs-crossover-temperature$0.002Developer Utilities
Gibbs free energy calculator
ΔG = ΔH − TΔS from enthalpy, entropy and temperature, free
POST /chem/gibbs-free-energy$0.002Developer Utilities
Gibbs energy from equilibrium constant calculator
ΔG° = −RT ln(K), free
POST /chem/gibbs-from-equilibrium$0.002Developer Utilities
Non-standard Gibbs free energy calculator
ΔG from ΔG°, Q, T
POST /chem/gibbs-non-standard$0.002Developer Utilities
Reaction spontaneity calculator
Gibbs ΔG from ΔH, ΔS, T
POST /chem/gibbs-spontaneity$0.002Developer Utilities
Graham's law calculator
effusion rate ratio from molar mass, free
POST /chem/graham-effusion-rate-ratio$0.002Developer Utilities
Graham effusion time calculator
t2 from t1 and molar masses, free
POST /chem/graham-effusion-time$0.002Developer Utilities
Unknown molar mass from effusion calculator
Graham's law free
POST /chem/graham-unknown-molar-mass$0.002Developer Utilities
Grams to moles calculator
n = m/M free
POST /chem/grams-to-moles$0.002Developer Utilities
Grams to particles calculator
mass and molar mass to N, free
POST /chem/grams-to-particles$0.002Developer Utilities
Half-life calculator
remaining amount after decay, free
POST /chem/half-life$0.002Developer Utilities
Number of half-lives calculator
elapsed time over t½, free
POST /chem/half-lives-elapsed$0.002Developer Utilities
Molar heat capacity ratio calculator
γ = Cp/Cv, free
POST /chem/heat-capacity-ratio$0.002Developer Utilities
Heat of neutralization calculator
molar ΔH from heat and moles of water
POST /chem/heat-of-neutralization$0.002Developer Utilities
Heat of solution calculator
molar ΔH_sol = q/n from heat and moles, free
POST /chem/heat-of-solution$0.002Developer Utilities
Heat required to raise temperature calculator
Q = m·c·ΔT from mass, c and ΔT, free
POST /chem/heat-to-raise-temperature$0.002Developer Utilities
Henderson–Hasselbalch calculator
buffer pH from pKa and ratio, free
POST /chem/henderson-hasselbalch$0.002Developer Utilities
Henry's law constant calculator
kH = c/p from concentration and partial pressure
POST /chem/henrys-law-constant$0.002Developer Utilities
Henry's law gas solubility calculator
c = k_H · p, free
POST /chem/henrys-law-solubility$0.002Developer Utilities
Hess's law calculator
overall reaction enthalpy from steps, free
POST /chem/hess-law$0.002Developer Utilities
Hydrate formula calculator
water of crystallization n from mass, free
POST /chem/hydrate-formula$0.002Developer Utilities
Hydrogen ion from weak acid calculator
[H+] from C and Ka, free
POST /chem/hydrogen-ion-weak-acid$0.002Developer Utilities
Hydroxide concentration from pOH calculator
[OH−] = 10^(−pOH)
POST /chem/hydroxide-from-poh$0.002Developer Utilities
Ideal gas law chemistry calculator
solve PV = nRT for P, V, n, or T
POST /chem/ideal-gas$0.002Developer Utilities
Integrated rate law order checker
which plot is linear, free
POST /chem/integrated-rate-order$0.002Developer Utilities
Internal energy change calculator
ΔU = Q − W first law, free
POST /chem/internal-energy-change$0.002Developer Utilities
Ionic strength calculator
I = ½ Σ c_i z_i² free
POST /chem/ionic-strength$0.002Developer Utilities
Isotope abundance calculator
percent from average mass, free
POST /chem/isotope-abundance$0.002Developer Utilities
Ka from pH calculator
acid dissociation from concentration and pH, free
POST /chem/ka-from-ph$0.002Developer Utilities
Kb from pKb calculator
base dissociation constant Kb = 10^(−pKb), free
POST /chem/kb-from-pkb$0.002Developer Utilities
Kc from degree of dissociation calculator
equilibrium constant from α and c₀, free
POST /chem/kc-from-dissociation$0.002Developer Utilities
Kp from Kc calculator
convert with T and Δn, free
POST /chem/kp-kc-conversion$0.002Developer Utilities
Lattice energy calculator
Born–Landé equation, free
POST /chem/lattice-energy-born-lande$0.002Developer Utilities
Product mass from limiting reactant calculator
two reagents, free
POST /chem/limiting-reactant-product-mass$0.002Developer Utilities
Mass fraction calculator
w and mass % from solute and total mass, free
POST /chem/mass-fraction$0.002Developer Utilities
Mass fraction to mole fraction calculator
free
POST /chem/mass-fraction-to-mole-fraction$0.002Developer Utilities
Pure mass from purity calculator
impure sample to pure substance mass, free
POST /chem/mass-from-purity$0.002Developer Utilities
Mass of element in sample calculator
m_element from sample mass and mass fraction, free
POST /chem/mass-of-element-in-sample$0.002Developer Utilities
Mass of product from reactant calculator
grams via mole ratio, free
POST /chem/mass-of-product-from-reactant$0.002Developer Utilities
Mass percent calculator
w/w concentration from solute and solution mass, free
POST /chem/mass-percent$0.002Developer Utilities
Mass percent to mole fraction calculator
free
POST /chem/mass-percent-to-mole-fraction$0.002Developer Utilities
Mass to gas volume stoichiometry calculator
product gas V from mass, free
POST /chem/mass-to-volume-gas-stoich$0.002Developer Utilities
Mixing three solutions calculator
final concentration free
POST /chem/mixing-three-solutions$0.002Developer Utilities
Mixing two solutions calculator
resulting concentration from C1 V1 + C2 V2
POST /chem/mixing-two-solutions$0.002Developer Utilities
Molality calculator
moles of solute per kg of solvent free
POST /chem/molality$0.002Developer Utilities
Molality calculator
moles of solute over kg solvent, free
POST /chem/molality-from-moles-mass$0.002Developer Utilities
Molality to molarity calculator
convert m to M with density, free
POST /chem/molality-to-molarity$0.002Developer Utilities
Molar mass calculator
formula to g/mol from atomic weights
POST /chem/molar-mass$0.002Developer Utilities
Molar mass from freezing point depression calculator
free
POST /chem/molar-mass-from-fp-depression$0.002Developer Utilities
Molar mass from osmotic pressure
van't Hoff M calculator, free
POST /chem/molar-mass-from-osmotic-pressure$0.002Developer Utilities
Molar solubility from Ksp calculator
s from Ksp and stoichiometry, free
POST /chem/molar-solubility-from-ksp$0.002Developer Utilities
Molar volume at STP calculator
ideal gas volume from moles at standard T and P, free
POST /chem/molar-volume-at-stp$0.002Developer Utilities
Molarity to mass percent calculator
M, density & MM to % w/w
POST /chem/molarity-to-mass-percent$0.002Developer Utilities
Molarity to normality calculator
N = M × equivalents per mole
POST /chem/molarity-to-normality$0.002Developer Utilities
Mole fraction calculator
x_i from component moles free
POST /chem/mole-fraction$0.002Developer Utilities
Mole fraction to molality calculator
convert x to m, free
POST /chem/mole-fraction-to-molality$0.002Developer Utilities
Mole fraction to molarity calculator
M from x, ρ free
POST /chem/mole-fraction-to-molarity$0.002Developer Utilities
Gas volume ratio calculator
stoichiometric volumes from coefficients, free
POST /chem/mole-ratio-gas-volumes$0.002Developer Utilities
Mole to mole conversion calculator
product moles from coefficients free
POST /chem/mole-to-mole-conversion$0.002Developer Utilities
Molecular formula calculator
empirical formula to molecular formula from molar mass free
POST /chem/molecular-formula$0.002Developer Utilities
Molecular formula from empirical calculator
multiplier n = M / M_emp free
POST /chem/molecular-from-empirical$0.002Developer Utilities
Moles to grams calculator
mass ↔ moles via molar mass, free
POST /chem/moles-from-mass$0.002Developer Utilities
Moles from molarity and volume calculator
n = M×V free
POST /chem/moles-from-molarity-volume$0.002Developer Utilities
Most probable molecular speed calculator
v_mp = √(2RT/M) free
POST /chem/most-probable-speed$0.002Developer Utilities
Nernst equation calculator
cell potential from E°, n, Q, free
POST /chem/nernst-equation$0.002Developer Utilities
Neutralization moles calculator
excess reagent from C and V
POST /chem/neutralization-moles$0.002Developer Utilities
Normality calculator
equivalents per liter of solution free
POST /chem/normality$0.002Developer Utilities
Normality to molarity calculator
M = N / n free
POST /chem/normality-to-molarity$0.002Developer Utilities
Number of atoms in sample calculator
N = (m/M)·N_A·n free
POST /chem/number-of-atoms-in-sample$0.002Developer Utilities
Osmolarity from osmotic pressure calculator
c = π/(RT) free
POST /chem/osmolarity-from-osmotic-pressure$0.002Developer Utilities
Osmotic pressure calculator
π = iCRT from concentration, T, and van 't Hoff factor
POST /chem/osmotic-pressure$0.002Developer Utilities
Osmotic pressure from molarity calculator
π = iMRT free
POST /chem/osmotic-pressure-from-molarity$0.002Developer Utilities
Osmotic pressure difference calculator
Δπ = (c₁−c₂)RT free
POST /chem/osmotic-pressure-two-solutions$0.002Developer Utilities
Partial pressure at new temperature calculator
p2 from p1, T1, T2 free
POST /chem/partial-pressure-change-temperature$0.002Developer Utilities
Partial pressure from mole fraction calculator
p_i = x_i·P free
POST /chem/partial-pressure-from-mole-fraction$0.002Developer Utilities
Particles to grams calculator
mass from count and molar mass, free
POST /chem/particles-to-grams$0.002Developer Utilities
Parts per thousand calculator
‰ from solute and total mass, free
POST /chem/parts-per-thousand$0.002Developer Utilities
Element percent by mass calculator
% composition from element mass and molar mass, free
POST /chem/percent-composition-element$0.002Developer Utilities
Percent dissociation calculator
% at equilibrium from C₀ and Ceq, free
POST /chem/percent-dissociation-equilibrium$0.002Developer Utilities
Percent ionization of acid calculator
% from C and Ka, free
POST /chem/percent-ionization$0.002Developer Utilities
Percent purity calculator
pure mass over sample mass, free
POST /chem/percent-purity$0.002Developer Utilities
Percent solution prep calculator
solute and solvent mass free
POST /chem/percent-solution-prep$0.002Developer Utilities
Mass percent to molarity calculator
% w/w, density & MM to M
POST /chem/percent-w-w-to-molarity$0.002Developer Utilities
Percent yield calculator
actual vs theoretical product mass, free
POST /chem/percent-yield-from-masses$0.002Developer Utilities
pH calculator
pH from hydrogen ion concentration [H+], free
POST /chem/ph-from-concentration$0.002Developer Utilities
pH from pOH calculator
pH = 14 − pOH at 25 °C, free
POST /chem/ph-from-poh$0.002Developer Utilities
pH to pOH calculator
pOH, [H+] and [OH−] at 25 °C
POST /chem/ph-poh-convert$0.002Developer Utilities
Weak acid pH calculator
approximate pH from concentration and Ka or pKa free
POST /chem/ph-weak-acid$0.002Developer Utilities
Weak base pH calculator
pH from concentration and Kb, free
POST /chem/ph-weak-base$0.002Developer Utilities
pKb from Kb calculator
pKb = −log10(Kb), free
POST /chem/pkb-from-kb$0.002Developer Utilities
pOH calculator
pOH and pH from [OH−] at 25 °C free
POST /chem/poh$0.002Developer Utilities
pOH calculator
pOH from hydroxide ion concentration [OH−], free
POST /chem/poh-from-hydroxide$0.002Developer Utilities
PPB to molarity calculator
convert ppb to M with density, free
POST /chem/ppb-to-molarity$0.002Developer Utilities
PPM calculator
parts per million from solute mass free
POST /chem/ppm-concentration$0.002Developer Utilities
PPM to mg/L calculator
concentration from density free
POST /chem/ppm-to-mg-per-liter$0.002Developer Utilities
PPM to molarity calculator
convert ppm and molar mass to mol/L
POST /chem/ppm-to-molarity$0.002Developer Utilities
PPM to PPB converter
parts per million to billion and trillion
POST /chem/ppm-to-ppb$0.002Developer Utilities
Pseudo-first-order rate constant calculator
k' from k and excess, free
POST /chem/pseudo-first-order$0.002Developer Utilities
Radioactive decay calculator
remaining quantity N(t)=N0·e^(−λt) free
POST /chem/radioactive-decay$0.002Developer Utilities
Raoult's law vapor pressure calculator
P = x·P° free
POST /chem/raoult-law-vapor-pressure$0.002Developer Utilities
Raoult's law two-component calculator
P = x₁P₁° + x₂P₂° free
POST /chem/raoult-two-component$0.002Developer Utilities
Rate constant at new temperature calculator
Arrhenius k2, free
POST /chem/rate-constant-new-temperature$0.002Developer Utilities
Rate from stoichiometry calculator
reaction rate from species rate and coefficient, free
POST /chem/rate-from-stoichiometry$0.002Developer Utilities
Rate law calculator
reaction rate from k and concentrations, free
POST /chem/rate-law$0.002Developer Utilities
Reactant mass needed calculator
grams for a target product, free
POST /chem/reactant-mass-for-product$0.002Developer Utilities
Reaction quotient Q calculator
Qc from concentrations and coefficients, free
POST /chem/reaction-quotient$0.002Developer Utilities
Reaction rate calculator
average rate from Δconcentration and time, free
POST /chem/reaction-rate$0.002Developer Utilities
Reduced properties calculator
Pr, Tr, Vr from critical constants
POST /chem/reduced-state-variables$0.002Developer Utilities
Relative vapor pressure lowering calculator
ΔP/P° free
POST /chem/relative-vapor-lowering$0.002Developer Utilities
Reverse osmosis net driving pressure
applied P minus feed osmotic π
POST /chem/reverse-osmosis-pressure$0.002Developer Utilities
Root-mean-square speed calculator
v_rms from molar mass and T, free
POST /chem/rms-speed$0.002Developer Utilities
Second-order concentration calculator
remaining [A] from k, A₀, t, free
POST /chem/second-order-concentration$0.002Developer Utilities
Second-order half-life calculator
t½ = 1/(k·[A]₀), free
POST /chem/second-order-half-life$0.002Developer Utilities
Serial dilution calculator
concentration at each step free
POST /chem/serial-dilution$0.002Developer Utilities
First-order shelf-life calculator
t90 for 10% decomposition, free
POST /chem/shelf-life-first-order$0.002Developer Utilities
Solution density from mass percent
ideal mixture estimate, free
POST /chem/solution-density-from-percent$0.002Developer Utilities
Solution freezing point calculator
Tf from solvent, molality, Kf and van't Hoff
POST /chem/solution-freezing-point$0.002Developer Utilities
Standard cell potential calculator
E° from cathode & anode, free
POST /chem/standard-cell-potential$0.002Developer Utilities
Stoichiometric air-fuel ratio calculator
AFR from C and H, free
POST /chem/stoichiometric-air-fuel-ratio$0.002Developer Utilities
Mole ratio calculator
product moles from stoichiometric coefficients free
POST /chem/stoichiometry-mole-ratio$0.002Developer Utilities
Theoretical yield calculator
moles × stoichiometric ratio, free
POST /chem/theoretical-yield$0.002Developer Utilities
Titration equivalence point volume calculator
Veq from C and V
POST /chem/titration-equivalence-volume$0.002Developer Utilities
Titration pH at equivalence calculator
salt C and Kb, free
POST /chem/titration-ph-at-equivalence$0.002Developer Utilities
Van der Waals molar volume calculator
real gas Vm from P, T, a, b
POST /chem/van-der-waals-volume$0.002Developer Utilities
Van't Hoff factor calculator
i from ions and dissociation, free
POST /chem/vant-hoff-factor$0.002Developer Utilities
Vapor phase composition calculator
Raoult y_i from x_i and P_i^sat, free
POST /chem/vapor-phase-composition$0.002Developer Utilities
Vapor pressure lowering calculator
ΔP = x·P° from mole fraction and pure solvent pressure
POST /chem/vapor-pressure-lowering$0.002Developer Utilities
Volume for target molarity calculator
V = n/M from moles, free
POST /chem/volume-for-target-molarity$0.002Developer Utilities
Volume percent to molarity calculator
M from % v/v free
POST /chem/volume-percent-to-molarity$0.002Developer Utilities
Gas volume to moles calculator
convert STP gas volume to moles free
POST /chem/volume-to-moles-gas$0.002Developer Utilities
Weight/volume percent calculator
% w/v from grams and mL, free
POST /chem/weight-volume-percent$0.002Developer Utilities
Weight-volume % to molarity calculator
% w/v to M, free
POST /chem/weight-volume-to-molarity$0.002Developer Utilities
Precipitation ion product calculator
Q vs Ksp, free
POST /chem/will-precipitate$0.002Developer Utilities
Analogous color generator
two neighbors by hue shift angle, free palette
POST /color/analogous$0.002Developer Utilities
CMYK to RGB converter
cyan magenta yellow key free
POST /color/cmyk-rgb$0.002Developer Utilities
Complementary color finder
opposite hue on the wheel, free
POST /color/complementary$0.002Developer Utilities
Color to grayscale converter
luminosity hex & gray value, free
POST /color/grayscale$0.002Developer Utilities
Hex to HSL converter
hue, saturation, lightness free
POST /color/hex-hsl$0.002Developer Utilities
Hex to color name
nearest CSS named color for any hex code, free
POST /color/hex-name$0.002Developer Utilities
Hex to RGB converter
#RRGGBB to red, green, blue, free
POST /color/hex-rgb$0.002Developer Utilities
HSL to HSV converter
convert hue saturation lightness and value both ways, free
POST /color/hsl-hsv$0.002Developer Utilities
HSL to RGB converter
hue, saturation, lightness to red green blue 0–255, free
POST /color/hsl-rgb$0.002Developer Utilities
HSV to RGB converter
hue, saturation, value to red, green, blue, free
POST /color/hsv-rgb$0.002Developer Utilities
Color lightener
lighten a hex color by percentage, free HSL tool
POST /color/lighten$0.002Developer Utilities
Color mixer
blend two hex colours by ratio, free
POST /color/mix$0.002Developer Utilities
CSS color name to hex
tomato, navy, rebeccapurple to #RRGGBB, free
POST /color/name-hex$0.002Developer Utilities
RGB to HSL converter
hue, saturation, lightness free
POST /color/rgb-hsl$0.002Developer Utilities
RGB to decimal integer
24-bit color pack free
POST /color/rgb-int$0.002Developer Utilities
Color shades generator
tints and shades by stepping HSL lightness, free
POST /color/shades$0.002Developer Utilities
Triadic color scheme generator
three hues at 120°, free
POST /color/triadic$0.002Developer Utilities
Combinations calculator
n choose r (binomial coefficient)
POST /combo/combinations$0.002Developer Utilities
Integer compositions calculator
ordered partitions into positive parts
POST /combo/compositions$0.002Developer Utilities
Derangement calculator
subfactorial !n, no fixed points
POST /combo/derangement$0.002Developer Utilities
Multinomial coefficient calculator
n! / (n1! n2! … nk!)
POST /combo/multinomial$0.002Developer Utilities
Integer partition calculator
p(n) ways to sum, free
POST /combo/partition-count$0.002Developer Utilities
Pascal's triangle generator
first n rows with exact BigInt entries
POST /combo/pascal-triangle$0.002Developer Utilities
Permutations calculator
P(n,r) = n!/(n−r)! with BigInt
POST /combo/permutations$0.002Developer Utilities
Permutations with repetition
n^r ordered selections, free
POST /combo/permutations-with-repetition$0.002Developer Utilities
Round-robin matches calculator
games and rounds for n teams
POST /combo/round-robin$0.002Developer Utilities
Stirling numbers of the second kind
S(n,k) partitions, free
POST /combo/stirling-second$0.002Developer Utilities
Acres to square meters converter
exact factor, free
POST /conv/acres-to-square-meters$0.002Developer Utilities
Physical action converter
J·s, eV·s, erg·s, h, ħ, free
POST /conv/action-physics$0.002Developer Utilities
Water alkalinity converter
mg/L CaCO3, meq/L, dKH, free
POST /conv/alkalinity$0.002Developer Utilities
Angular momentum converter
kg·m²/s, g·cm²/s, J·s, free
POST /conv/angular-momentum$0.002Developer Utilities
API gravity converter
°API, specific gravity and density, free
POST /conv/api-gravity$0.002Developer Utilities
ATM to PSI converter
exact atmosphere factor, free
POST /conv/atm-to-psi$0.002Developer Utilities
Beaufort scale converter
force, knots, mph, m/s, free
POST /conv/beaufort-wind$0.002Developer Utilities
Belt size converter
waist in/cm, numeric belt & letter, free
POST /conv/belt-size$0.002Developer Utilities
Binary prefix converter
kibi, mebi, gibi vs kilo, free
POST /conv/binary-prefix$0.002Developer Utilities
BTU to kWh converter
exact International Table factor, free
POST /conv/btu-to-kwh$0.002Developer Utilities
Calories to joules converter
exact 4.184 factor, free
POST /conv/calories-to-joules$0.002Developer Utilities
Calorific value converter
MJ/m³, BTU/ft³, kcal/L, free
POST /conv/calorific-value$0.002Developer Utilities
CM to inches converter
exact 2.54 factor, free
POST /conv/cm-to-inches$0.002Developer Utilities
Color depth converter
bpp, colors, bits/channel, free
POST /conv/color-depth$0.002Developer Utilities
Cubic meters to cubic feet converter
exact factor, free
POST /conv/cubic-meters-to-cubic-feet$0.002Developer Utilities
Degrees to gradians converter
exact deg × 10/9, free
POST /conv/degrees-to-gradians$0.002Developer Utilities
Didot point converter
cicero, mm and PostScript points, free
POST /conv/didot-point$0.002Developer Utilities
Electric flux converter
V·m, N·m²/C, C/ε₀, statV·cm, free
POST /conv/electric-flux$0.002Developer Utilities
Electron mobility converter
m²/(V·s), cm²/(V·s), free
POST /conv/electron-mobility$0.002Developer Utilities
Entropy converter
J/K, cal/K, BTU/R and more, free
POST /conv/entropy$0.002Developer Utilities
Equivalent weight converter
g/eq, kg/eq, mg/meq, free
POST /conv/equivalent-weight$0.002Developer Utilities
Fabric weight converter
gsm, oz/yd², oz/ft², free
POST /conv/fabric-weight$0.002Developer Utilities
Fahrenheit to Rankine converter
exact F+459.67, free
POST /conv/fahrenheit-to-rankine$0.002Developer Utilities
Film speed converter
ISO, ASA, DIN and more, free
POST /conv/film-speed$0.002Developer Utilities
Foot-pounds to newton-meters converter
exact factor, free
POST /conv/foot-pounds-to-newton-meters$0.002Developer Utilities
Gallons to cups converter
exact US factor, free
POST /conv/gallons-to-cups$0.002Developer Utilities
Gallons to quarts converter
exact US factor, free
POST /conv/gallons-to-quarts$0.002Developer Utilities
Glove size converter
cm, inches and numeric size, free
POST /conv/glove-size$0.002Developer Utilities
Hardness scale converter
Rockwell, Brinell, Vickers, free
POST /conv/hardness$0.002Developer Utilities
Hectares to acres converter
exact factor, free
POST /conv/hectares-to-acres$0.002Developer Utilities
Humidity ratio converter
kg/kg, grains/lb, g/kg and more, free
POST /conv/humidity-ratio$0.002Developer Utilities
Hydraulic conductivity converter
m/s, cm/h, gpd/ft², free
POST /conv/hydraulic-conductivity$0.002Developer Utilities
Imperial gallons to US gallons converter
exact factor, free
POST /conv/imperial-gallons-to-us-gallons$0.002Developer Utilities
Inches to cm converter
convert inches to centimeters, free
POST /conv/inches-to-cm$0.002Developer Utilities
Jerk converter
m/s³, ft/s³, g/s and more, free
POST /conv/jerk$0.002Developer Utilities
Joules to foot-pounds converter
exact factor, free
POST /conv/joules-to-foot-pounds$0.002Developer Utilities
kg/m³ to lb/ft³ converter
exact density factor, free
POST /conv/kg-per-m3-to-lb-per-ft3$0.002Developer Utilities
KG to stone converter
exact factor, free in browser
POST /conv/kg-to-stone$0.002Developer Utilities
KM to miles converter
exact factor, free in browser
POST /conv/km-to-miles$0.002Developer Utilities
Knots to km/h converter
exact 1.852 factor, free in browser
POST /conv/knots-to-kmh$0.002Developer Utilities
kW to hp converter
exact mechanical horsepower factor, free
POST /conv/kw-to-hp$0.002Developer Utilities
Lbs to ounces converter
exact 16 oz factor, free
POST /conv/lbs-to-ounces$0.002Developer Utilities
Vacuum leak rate converter
mbar·L/s, sccm, atm·cc/s, free
POST /conv/leak-rate$0.002Developer Utilities
Linear mass density converter
kg/m, g/m, lb/ft and more, free
POST /conv/linear-density$0.002Developer Utilities
Linear energy transfer converter
keV/μm, MeV/cm, J/m, free
POST /conv/linear-energy-transfer$0.002Developer Utilities
Nominal lumber size converter
actual inches & mm, free
POST /conv/lumber-size$0.002Developer Utilities
Luminous energy converter
lm·s, talbot, lm·h, free
POST /conv/luminous-energy$0.002Developer Utilities
Luminous exposure converter
lux·s, lux·h, phot·s, free
POST /conv/luminous-exposure$0.002Developer Utilities
Magnetic moment converter
A·m², μB, erg/G, J/T, free
POST /conv/magnetic-moment$0.002Developer Utilities
Magnetic susceptibility converter
SI/CGS volume, mass & molar, free
POST /conv/magnetic-susceptibility$0.002Developer Utilities
Magnetomotive force converter
ampere-turns, gilberts, abampere-turns, free
POST /conv/magnetomotive-force$0.002Developer Utilities
Mass diffusivity converter
m²/s, cm²/s, ft²/h, free
POST /conv/mass-diffusivity$0.002Developer Utilities
Mass flux converter
kg/(m²·s), g/(cm²·s) and more, free
POST /conv/mass-flux$0.002Developer Utilities
Meters per second to mph
exact factor, free in browser
POST /conv/meters-per-second-to-mph$0.002Developer Utilities
Meters to inches converter
exact factor, free in browser
POST /conv/meters-to-inches$0.002Developer Utilities
Meters to yards converter
exact factor, free in browser
POST /conv/meters-to-yards$0.002Developer Utilities
Metric tons to US tons converter
exact factor, free in browser
POST /conv/metric-tons-to-us-tons$0.002Developer Utilities
Miles to yards converter
exact factor, free in browser
POST /conv/miles-to-yards$0.002Developer Utilities
ML to teaspoons converter
exact 5 ml factor, free
POST /conv/ml-to-teaspoons$0.002Developer Utilities
Molar conductivity converter
S·m²/mol, S·cm²/mol, free
POST /conv/molar-conductivity$0.002Developer Utilities
Molar entropy converter
J/(mol·K), cal/(mol·K), eu, free
POST /conv/molar-entropy$0.002Developer Utilities
Molar flow rate converter
mol/s, mol/h, kmol/h, free
POST /conv/molar-flow-rate$0.002Developer Utilities
Molar volume converter
m³/mol, L/mol, mL/mol and more, free
POST /conv/molar-volume$0.002Developer Utilities
Nuclear cross section converter
barn, m², cm², free
POST /conv/nuclear-cross-section$0.002Developer Utilities
Numerical aperture converter
NA, f-number and acceptance angle, free
POST /conv/numerical-aperture$0.002Developer Utilities
Parsecs to light-years converter
exact IAU factor, free
POST /conv/parsecs-to-light-years$0.002Developer Utilities
Permeability converter
darcy, millidarcy, m² and more, free
POST /conv/permeability-darcy$0.002Developer Utilities
Permittivity converter
F/m, ε_r, pF/m, free
POST /conv/permittivity$0.002Developer Utilities
Photon energy converter
eV, nm wavelength, THz, free
POST /conv/photon-energy$0.002Developer Utilities
Pressure unit converter
Pa, kPa, bar, atm, psi, mmHg and torr, free
POST /conv/pressure$0.002Developer Utilities
Pressure altitude converter
hPa, inHg, meters and more, free
POST /conv/pressure-altitude$0.002Developer Utilities
Pressure head converter
mH2O, ftH2O, psi and more, free
POST /conv/pressure-head$0.002Developer Utilities
Rainfall rate converter
mm/h, in/h, L/m²/h, free
POST /conv/rainfall-rate$0.002Developer Utilities
Audio sample rate converter
Hz, kHz, sps, free
POST /conv/sample-rate$0.002Developer Utilities
Screw gauge size converter
US #, mm & inch diameter, free
POST /conv/screw-size$0.002Developer Utilities
Section modulus converter
m³, cm³, mm³, in³, free
POST /conv/section-modulus$0.002Developer Utilities
Sheet metal gauge converter
gauge, mm, inches, free
POST /conv/sheet-metal-gauge$0.002Developer Utilities
Shutter speed converter
fraction, seconds, stops, free
POST /conv/shutter-speed$0.002Developer Utilities
Sieve mesh size converter
US, Tyler, micron, free
POST /conv/sieve-mesh$0.002Developer Utilities
Solar mass, radius & luminosity converter
SI units, free
POST /conv/solar-units$0.002Developer Utilities
Sound absorption converter
sabins ↔ metric sabins ↔ m², free
POST /conv/sound-absorption$0.002Developer Utilities
Sound power converter
W, dB re 1 pW, BTU/h, free
POST /conv/sound-power$0.002Developer Utilities
Specific impulse converter
seconds, m/s exhaust velocity, lbf·s/lb, free
POST /conv/specific-impulse$0.002Developer Utilities
Square km to square miles
exact factor, free in browser
POST /conv/square-km-to-square-miles$0.002Developer Utilities
Spring stiffness converter
N/m, lbf/in, kg/mm, free
POST /conv/stiffness$0.002Developer Utilities
Guitar string gauge converter
mils, mm & inches, free
POST /conv/string-gauge$0.002Developer Utilities
Surface charge density converter
C/m², C/cm², C/in², free
POST /conv/surface-charge-density$0.002Developer Utilities
Thermal conductance converter
W/K, BTU/(h·°F), cal/(s·K), free
POST /conv/thermal-conductance$0.002Developer Utilities
Thermal expansion coefficient converter
1/K, ppm/K, 1/°F, free
POST /conv/thermal-expansion-coefficient$0.002Developer Utilities
Thread count converter
TPI, threads/cm, per 10 cm and more, free
POST /conv/thread-count$0.002Developer Utilities
Thread pitch converter
TPI, mm pitch and threads/cm, free
POST /conv/thread-pitch$0.002Developer Utilities
Torr to PSI converter
exact torr factor, free
POST /conv/torr-to-psi$0.002Developer Utilities
Turbidity converter
NTU, FNU, FTU, JTU, free
POST /conv/turbidity$0.002Developer Utilities
Vacuum pressure converter
torr, mbar, Pa, micron, free
POST /conv/vacuum$0.002Developer Utilities
Water conductivity & TDS converter
µS/cm, ppm, gpg, free
POST /conv/water-conductivity$0.002Developer Utilities
Cups to grams converter
flour, sugar, butter and more by ingredient density, free
POST /cook/cups-grams$0.002Developer Utilities
Fluid ounces to ml converter
US and imperial fl oz ↔ milliliters, free
POST /cook/fl-oz-ml$0.002Developer Utilities
Flour cups to grams converter
all-purpose, bread & cake, free
POST /cook/flour$0.002Developer Utilities
Gas mark converter
oven °C & °F from Gas Mark, free
POST /cook/gas-mark$0.002Developer Utilities
Grams to cups converter
by ingredient density, free
POST /cook/grams-cups$0.002Developer Utilities
mL to cups converter
US, metric & imperial cups, free
POST /cook/ml-cups$0.002Developer Utilities
Oven temperature converter
Celsius, Fahrenheit and oven heat labels, free
POST /cook/oven-temp$0.002Developer Utilities
Cooking ounces to grams converter
kitchen weight oz ↔ g, free
POST /cook/oz-grams$0.002Developer Utilities
Quarts to liters converter
US & imperial quarts, free
POST /cook/quarts-liters$0.002Developer Utilities
Recipe scaler
scale ingredient amounts by servings or multiplier, free
POST /cook/recipe-scale$0.002Developer Utilities
Rice cups to grams converter
raw or cooked, free
POST /cook/rice$0.002Developer Utilities
Sugar cups to grams converter
granulated, brown and powdered by density, free
POST /cook/sugar$0.002Developer Utilities
Tablespoons to ml converter
US, metric & Australian tbsp, free
POST /cook/tbsp-ml$0.002Developer Utilities
US to metric cooking converter
cups, tbsp, fl oz ↔ ml, g, free
POST /cook/us-metric$0.002Developer Utilities
Yeast conversion converter
active dry, instant & fresh, free
POST /cook/yeast$0.002Developer Utilities
Add days to a date
ISO calendar date plus or minus N days, free
POST /date/add-days$0.002Developer Utilities
Add years to a date
ISO calendar date plus or minus N years, free
POST /date/add-years$0.002Developer Utilities
Birth flower by month
traditional birth flowers for each month
POST /date/birth-flower$0.002Developer Utilities
Chinese zodiac element calculator
animal + five-element year in the 60-year cycle, free
POST /date/chinese-zodiac-element$0.002Developer Utilities
Countdown between two dates
days hours minutes seconds, free
POST /date/countdown-between$0.002Developer Utilities
Day of year to date converter
ordinal 1–366 to calendar YYYY-MM-DD, free
POST /date/date-from-dayofyear$0.002Developer Utilities
Day of the week calculator
name and number from an ISO date
POST /date/day-of-week$0.002Developer Utilities
Day of the year calculator
ISO date to ordinal day 1–366, free
POST /date/day-of-year$0.002Developer Utilities
Days in a month calculator
leap years included, free
POST /date/days-in-month$0.002Developer Utilities
Days left in the year
remaining days until December 31, free
POST /date/days-remaining-year$0.002Developer Utilities
Decade and century finder
year to 2020s & 21st, free
POST /date/decade-century$0.002Developer Utilities
Dominical letter calculator
Gregorian A–G (or two letters in leap years), free
POST /date/dominical-letter$0.002Developer Utilities
Doomsday rule calculator
Conway weekday from ISO date, free
POST /date/doomsday-weekday$0.002Developer Utilities
Orthodox Easter date calculator
Julian computus to Gregorian, free
POST /date/easter-orthodox$0.002Developer Utilities
Friday the 13th finder
every Friday the 13th in a year, free
POST /date/friday-13th$0.002Developer Utilities
Humanize duration
seconds to days, hours, minutes (readable)
POST /date/humanize-duration$0.002Developer Utilities
Leap year checker
Gregorian leap test and divisibility reason
POST /date/is-leap-year$0.002Developer Utilities
ISO weekday number
Monday=1 to Sunday=7 from an ISO date
POST /date/iso-weekday-number$0.002Developer Utilities
Julian Day Number calculator
ISO date to astronomical JDN, free
POST /date/julian-day-number$0.002Developer Utilities
Last weekday of the month
final Monday–Sunday date, free
POST /date/last-weekday-of-month$0.002Developer Utilities
Leap years in a range
count and list Gregorian leap years between two years, free
POST /date/leap-years-between$0.002Developer Utilities
Printable month calendar generator
weeks layout, free
POST /date/month-calendar$0.002Developer Utilities
Months between two dates
whole months and remaining days, free
POST /date/months-between$0.002Developer Utilities
Nth weekday of the month
third Monday, last Friday and any ordinal date, free
POST /date/nth-weekday-of-month$0.002Developer Utilities
ISO ordinal date converter
YYYY-MM-DD ↔ YYYY-DDD, free
POST /date/ordinal-date$0.002Developer Utilities
Previous weekday occurrence
most recent Monday–Sunday before a date, free
POST /date/previous-weekday$0.002Developer Utilities
Calendar quarter finder
ISO date to Q1–Q4 with start and end dates, free
POST /date/quarter-of-year$0.002Developer Utilities
Quarter start and end dates
Q1–Q4 calendar range, free
POST /date/quarter-start-end$0.002Developer Utilities
Recurring dates generator
every N days from start to end, free
POST /date/recurring-dates$0.002Developer Utilities
Season of the year calculator
meteorological season by hemisphere
POST /date/season$0.002Developer Utilities
US week number calculator
Sunday start, week 1 has Jan 1
POST /date/us-week-number$0.002Developer Utilities
Week start and end dates
ISO date plus first weekday to Monday–Sunday range, free
POST /date/week-start-end$0.002Developer Utilities
Weekday count in a year
how many Mondays, free
POST /date/weekday-frequency$0.002Developer Utilities
Weekend days between two dates
count Saturdays and Sundays in a date range, free
POST /date/weekend-count$0.002Developer Utilities
Weeks between two dates
whole weeks and leftover days from ISO dates, free
POST /date/weeks-between$0.002Developer Utilities
Year progress percentage
ISO date to % of calendar year elapsed, free
POST /date/year-progress$0.002Developer Utilities
Zeller's congruence calculator
weekday from ISO date, step by step
POST /date/zeller-weekday$0.002Developer Utilities
Zodiac element calculator
birth date to fire, earth, air, water
POST /date/zodiac-element$0.002Developer Utilities
Western zodiac sign calculator
birth date to sign, free
POST /date/zodiac-sign$0.002Developer Utilities
AWG ampacity calculator
max safe current by wire gauge
POST /elec/awg-ampacity$0.002Developer Utilities
AWG wire gauge calculator
diameter, area and ohms per metre, free
POST /elec/awg-wire$0.002Developer Utilities
Battery life calculator
runtime hours from mAh capacity and mA draw, free
POST /elec/battery-life$0.002Developer Utilities
Capacitive reactance calculator
Xc=1/(2πfC) in ohms, free
POST /elec/capacitive-reactance$0.002Developer Utilities
Capacitor charge calculator
Q=CV stored charge from C and V, free
POST /elec/capacitor-charge$0.002Developer Utilities
Capacitor charging calculator
V(t)=Vs(1−e^(−t/RC)) voltage during charge, free
POST /elec/capacitor-charge-time$0.002Developer Utilities
Parallel capacitance calculator
total C for capacitors in parallel
POST /elec/capacitors-parallel$0.002Developer Utilities
Series capacitance calculator
capacitors in series, free
POST /elec/capacitors-series$0.002Developer Utilities
Electric charge calculator
Q=It solve charge, current or time
POST /elec/charge-current-time$0.002Developer Utilities
Coulomb's law calculator
electrostatic force between two charges
POST /elec/coulombs-law$0.002Developer Utilities
Current divider calculator
branch currents for two parallel resistors, free
POST /elec/current-divider$0.002Developer Utilities
Electric field force calculator
F = qE, free in browser
POST /elec/electric-field-force$0.002Developer Utilities
Electric field calculator
E=kQ/r² point charge magnitude, free
POST /elec/electric-field-point$0.002Developer Utilities
Electricity cost calculator
appliance energy use and running cost
POST /elec/electrical-energy-cost$0.002Developer Utilities
Frequency period converter
T = 1/f and f = 1/T, free
POST /elec/frequency-period$0.002Developer Utilities
Inductive reactance calculator
XL = 2πfL in ohms, free
POST /elec/inductive-reactance$0.002Developer Utilities
LC resonant frequency calculator
f₀ = 1/(2π√(LC)), free
POST /elec/lc-resonant-frequency$0.002Developer Utilities
LED resistor calculator
series resistor and power rating
POST /elec/led-resistor$0.002Developer Utilities
Magnetic field of a straight wire calculator
B = μ₀I/(2πr), free
POST /elec/magnetic-field-wire$0.002Developer Utilities
Magnetic force calculator
Lorentz F=qvB sinθ on a moving charge, free
POST /elec/magnetic-force-charge$0.002Developer Utilities
Force on a current-carrying wire calculator
F = I L B sin(θ)
POST /elec/magnetic-force-wire$0.002Developer Utilities
555 timer calculator
astable frequency and duty cycle
POST /elec/ne555-astable$0.002Developer Utilities
555 timer monostable calculator
pulse width t=1.1RC, free
POST /elec/ne555-monostable$0.002Developer Utilities
Non-inverting amplifier calculator
gain Av = 1 + Rf/Rg, free
POST /elec/op-amp-noninverting$0.002Developer Utilities
Parallel-plate capacitor calculator
C from area, gap and dielectric
POST /elec/parallel-plate-capacitance$0.002Developer Utilities
Power gain dB calculator
G = 10·log10(Pout/Pin) from input and output power, free
POST /elec/power-gain-db$0.002Developer Utilities
PWM duty cycle calculator
on-time, period, average voltage, free
POST /elec/pwm-duty-cycle$0.002Developer Utilities
RC filter cutoff calculator
fc = 1/(2πRC) for LP/HP filters
POST /elec/rc-filter-cutoff$0.002Developer Utilities
RC time constant calculator
τ=RC and 5τ settling time, free
POST /elec/rc-time-constant$0.002Developer Utilities
Wire resistance calculator
R = ρL/A from resistivity, free
POST /elec/resistivity$0.002Developer Utilities
Series resistance calculator
total ohms for resistors in series, free
POST /elec/resistors-series$0.002Developer Utilities
RL filter cutoff calculator
fc=R/(2πL) in hertz, free
POST /elec/rl-filter-cutoff$0.002Developer Utilities
RL time constant calculator
τ = L/R for series RL circuits
POST /elec/rl-time-constant$0.002Developer Utilities
Slew rate from full-power bandwidth
SR=2πfVpeak op-amp calculator, free
POST /elec/slew-rate-bandwidth$0.002Developer Utilities
Johnson noise calculator
RMS thermal noise voltage √(4kTRΔf), free
POST /elec/thermal-noise$0.002Developer Utilities
Voltage drop calculator
AWG wire, length, current, free
POST /elec/voltage-drop-wire$0.002Developer Utilities
Voltage gain dB calculator
Av = 20·log10(Vout/Vin)
POST /elec/voltage-gain-db$0.002Developer Utilities
Watts to dBm calculator
convert power in W or mW to dBm, free
POST /elec/watts-to-dbm$0.002Developer Utilities
Watts, volts & amps calculator
solve power, voltage or current
POST /elec/watts-volts-amps$0.002Developer Utilities
Frequency to wavelength calculator
free-space RF λ = c/f, free
POST /elec/wavelength-frequency-rf$0.002Developer Utilities
Wheatstone bridge calculator
find unknown resistance Rx, free
POST /elec/wheatstone-bridge$0.002Developer Utilities
Zener diode resistor calculator
series resistor value and power rating, free
POST /elec/zener-resistor$0.002Developer Utilities
Affine cipher
encrypt or decrypt with keys a and b, free
POST /enc/affine$0.002Developer Utilities
ASCII code lookup
character to decimal, hex and octal, free
POST /enc/ascii-lookup$0.002Developer Utilities
Atbash cipher
mirror the alphabet (A↔Z), free online
POST /enc/atbash$0.002Developer Utilities
Autokey cipher
encrypt or decrypt text with a keyword extended by the message, free
POST /enc/autokey$0.002Developer Utilities
Base16 RFC 4648 encoder & decoder
uppercase hex, free
POST /enc/base16-rfc4648$0.002Developer Utilities
Base32 encoder & decoder
RFC 4648 A-Z and 2-7, free
POST /enc/base32$0.002Developer Utilities
Base58 encoder & decoder
Bitcoin alphabet, free online
POST /enc/base58$0.002Developer Utilities
Flickr Base58 encoder & decoder
short URL alphabet, free
POST /enc/base58-flickr$0.002Developer Utilities
Text to Base64
encode or decode with standard padding, free
POST /enc/base64$0.002Developer Utilities
Ascii85 / Base85 encoder
encode or decode text, free
POST /enc/base85$0.002Developer Utilities
Beaufort cipher
encrypt or decrypt text with a keyword, free
POST /enc/beaufort$0.002Developer Utilities
Bifid cipher
encrypt or decrypt text with Polybius fractionation and a keyword, free
POST /enc/bifid$0.002Developer Utilities
Text to binary converter
8-bit encode & decode, free
POST /enc/binary-text$0.002Developer Utilities
Braille translator
text to Unicode Braille (Grade 1) and back, free
POST /enc/braille$0.002Developer Utilities
Caesar cipher
encrypt or decrypt text with a letter shift, free
POST /enc/caesar$0.002Developer Utilities
Gronsfeld cipher
encrypt & decrypt with a numeric key, free
POST /enc/gronsfeld$0.002Developer Utilities
Text to hex converter
encode or decode UTF-8 bytes, free
POST /enc/hex-text$0.002Developer Utilities
Keyboard shift cipher
QWERTY adjacent-key encrypt or decrypt, free
POST /enc/keyboard-shift$0.002Developer Utilities
Leetspeak translator
convert text to 1337 speak and back, free
POST /enc/leetspeak$0.002Developer Utilities
Multiplicative cipher
encrypt & decrypt with a coprime key, free
POST /enc/multiplicative$0.002Developer Utilities
NATO phonetic alphabet
spell or decode Alpha Bravo Charlie, free
POST /enc/nato$0.002Developer Utilities
Nihilist cipher
encrypt or decrypt with Polybius square keyword and numeric key, free
POST /enc/nihilist$0.002Developer Utilities
Text to octal converter
encode UTF-8 bytes as base-8, free
POST /enc/octal-text$0.002Developer Utilities
Playfair cipher
encrypt & decrypt with a keyword square, free
POST /enc/playfair$0.002Developer Utilities
Polybius square cipher
encrypt or decrypt letters as row-column digit pairs, free
POST /enc/polybius$0.002Developer Utilities
Punycode converter
encode Unicode domains to xn--, free
POST /enc/punycode$0.002Developer Utilities
Rail fence cipher
encrypt or decrypt zigzag transposition, free
POST /enc/rail-fence$0.002Developer Utilities
ROT13 encoder
rotate letters by 13, free online
POST /enc/rot13$0.002Developer Utilities
ROT18 cipher
ROT13 letters + ROT5 digits, free online
POST /enc/rot18$0.002Developer Utilities
ROT5 digit cipher
rotate 0–9 by five, free online
POST /enc/rot5$0.002Developer Utilities
Tap code translator
Polybius encode & decode, free
POST /enc/tap-code$0.002Developer Utilities
Trifid cipher
encrypt or decrypt with a 27-symbol cube, free
POST /enc/trifid$0.002Developer Utilities
Unicode code point converter
characters ↔ U+XXXX, free
POST /enc/unicode-codepoint$0.002Developer Utilities
URL percent encoder & decoder
escape reserved characters, free
POST /enc/url$0.002Developer Utilities
UTF-8 byte encoder
text to hex bytes & decode, free
POST /enc/utf8-bytes$0.002Developer Utilities
XOR cipher
encrypt or decrypt with a repeating key, free online
POST /enc/xor$0.002Developer Utilities
Base62 number converter
integer to or from base-62 (0-9A-Za-z), free
POST /fmt/base62$0.002Developer Utilities
Binary to hex converter
base-2 string to base-16 value, free
POST /fmt/binary-hex$0.002Developer Utilities
Chinese number converter
everyday & financial numerals
POST /fmt/chinese-numerals$0.002Developer Utilities
Number to currency words
spell money for cheque writing (e.g. 1250.50 → one thousand two hundred fifty and 50/100), free
POST /fmt/currency-words$0.002Developer Utilities
Decimal to binary converter
whole number to base-2 string, free
POST /fmt/decimal-binary$0.002Developer Utilities
Decimal to fraction converter
reduced numerator/denominator, free
POST /fmt/decimal-fraction$0.002Developer Utilities
Decimal to octal converter
base-10 to base-8, free
POST /fmt/decimal-octal$0.002Developer Utilities
Decimal to percent converter
0.25 to 25%, free online
POST /fmt/decimal-percent$0.002Developer Utilities
Duodecimal converter
base-10 ↔ base-12 with dek (X) and el (E), free
POST /fmt/duodecimal$0.002Developer Utilities
Fraction to decimal converter
turn a/b into a decimal value, free
POST /fmt/fraction-decimal$0.002Developer Utilities
Gray code converter
binary ↔ reflected Gray, free
POST /fmt/gray-code$0.002Developer Utilities
Hex to binary converter
base-16 string to base-2 bits, free
POST /fmt/hex-binary$0.002Developer Utilities
Hex to decimal converter
base-16 string to integer, free
POST /fmt/hex-decimal$0.002Developer Utilities
Float to IEEE-754 converter
hex and binary bit pattern, free
POST /fmt/ieee754$0.002Developer Utilities
Spell a number in English
words for integers, decimals, negatives
POST /fmt/number-to-words-en$0.002Developer Utilities
Spell a number in Spanish
formal words for any integer, free
POST /fmt/number-to-words-es$0.002Developer Utilities
Percent to decimal converter
percentage to decimal (e.g. 25% → 0.25), free
POST /fmt/percent-decimal$0.002Developer Utilities
Large Roman numerals converter
vinculum overlines above 3999, free
POST /fmt/roman-large$0.002Developer Utilities
Number rounding tool
decimals, nearest ten, hundred or thousand, free
POST /fmt/rounding$0.002Developer Utilities
Scientific notation converter
decimal ↔ mantissa×10^n, free
POST /fmt/scientific-notation$0.002Developer Utilities
Ordinal words converter
spell 1st, 21st, 100th in English
POST /fmt/spell-ordinal$0.002Developer Utilities
Thai numeral converter
Western digits ↔ Thai ๐-๙ integers, free
POST /fmt/thai-numerals$0.002Developer Utilities
Add thousands separators
format numbers with grouped digits, free
POST /fmt/thousands-separator$0.002Developer Utilities
Two's complement converter
signed integer ↔ fixed-width binary, free
POST /fmt/twos-complement$0.002Developer Utilities
Antipode coordinates calculator
opposite point on Earth from lat/lon, free
POST /geo/antipode$0.002Developer Utilities
Bearing to compass direction
degrees to N, NNE, NE… free
POST /geo/bearing-to-compass$0.002Developer Utilities
Point-radius bounding box
min/max lat lon from center, free
POST /geo/bounding-box$0.002Developer Utilities
Cross-track distance calculator
signed offset from a great-circle path, free
POST /geo/cross-track-distance$0.002Developer Utilities
Decimal degrees to DMS converter
degrees, minutes, seconds and hemisphere, free
POST /geo/decimal-to-dms$0.002Developer Utilities
Length of a degree of latitude
WGS-84 ground distance, free
POST /geo/degree-length-latitude$0.002Developer Utilities
Length of a degree of longitude
ground distance at any latitude (WGS84), free
POST /geo/degree-length-longitude$0.002Developer Utilities
Destination point calculator
great-circle lat/lon from bearing and distance, free
POST /geo/destination-point$0.002Developer Utilities
DMS to decimal degrees converter
hemisphere letter, free
POST /geo/dms-to-decimal$0.002Developer Utilities
Equirectangular distance
fast lat/lon distance approximation, free
POST /geo/equirectangular-distance$0.002Developer Utilities
Great-circle interpolation
intermediate lat/lon between two points, free
POST /geo/geodesic-interpolate$0.002Developer Utilities
Geohash bounding box
lat/lon corners from geohash, free
POST /geo/geohash-bbox$0.002Developer Utilities
Geohash neighbors finder
8 adjacent cells, free
POST /geo/geohash-neighbors$0.002Developer Utilities
Web map scale calculator
zoom, latitude & DPI to 1:N, free
POST /geo/map-scale$0.002Developer Utilities
Web Mercator meters per pixel
ground resolution from zoom and latitude, free
POST /geo/meters-per-pixel$0.002Developer Utilities
Lat lon to MGRS
military grid reference from coordinates, free
POST /geo/mgrs-from-latlon$0.002Developer Utilities
MGRS to lat/lon
military grid reference south-west corner to WGS84, free
POST /geo/mgrs-to-latlon$0.002Developer Utilities
Point in polygon checker
test if a point lies inside a polygon, free
POST /geo/point-in-polygon$0.002Developer Utilities
Polygon centroid calculator
area-weighted lat/lon center
POST /geo/polygon-centroid$0.002Developer Utilities
Bing Maps quadkey decoder
tile X, Y and zoom from a quadkey string, free
POST /geo/quadkey-decode$0.002Developer Utilities
Tile to Bing Maps quadkey
X/Y/zoom to quadkey string, free
POST /geo/quadkey-encode$0.002Developer Utilities
Rhumb line bearing calculator
constant course between two points, free
POST /geo/rhumb-bearing$0.002Developer Utilities
Rhumb line destination point
lat/lon from constant bearing and distance, free
POST /geo/rhumb-destination$0.002Developer Utilities
Lat/lon to map tile
Web Mercator slippy X/Y from coordinates and zoom, free
POST /geo/tile-from-latlon$0.002Developer Utilities
Lat lon to UTM converter
zone, easting, northing, free
POST /geo/utm-from-latlon$0.002Developer Utilities
Vincenty distance calculator
WGS-84 ellipsoidal geodesic, free
POST /geo/vincenty-distance$0.002Developer Utilities
Web Mercator unproject
meters to lat/lon (EPSG:3857), free
POST /geo/web-mercator-unproject$0.002Developer Utilities
Arc length calculator
sector area from radius and central angle
POST /geom/arc-length$0.002Developer Utilities
Barrel volume calculator
estimate cask volume from top radius, middle radius and height
POST /geom/barrel$0.002Developer Utilities
Circle equation calculator
standard & general form, area, circumference
POST /geom/circle-equation$0.002Developer Utilities
Circle–line intersection
find 0, 1 or 2 points from center, radius and line
POST /geom/circle-line-intersection$0.002Developer Utilities
Cube calculator
volume, surface area and diagonals from edge, volume or area
POST /geom/cube$0.002Developer Utilities
Cylinder volume calculator
lateral and total surface area from radius and height
POST /geom/cylinder$0.002Developer Utilities
Distance between two points
Euclidean 2D calculator, free
POST /geom/distance-2d$0.002Developer Utilities
Ellipsoid volume calculator
surface area by Knud Thomsen from three semi-axes
POST /geom/ellipsoid$0.002Developer Utilities
Conical frustum calculator
volume, slant height and surface area from two radii and height
POST /geom/frustum-cone$0.002Developer Utilities
Pyramid frustum calculator
volume from two base areas and height, free
POST /geom/frustum-pyramid$0.002Developer Utilities
Hemisphere calculator
volume, curved and total surface area, free
POST /geom/hemisphere$0.002Developer Utilities
Heron's formula calculator
triangle area from three side lengths
POST /geom/heron-area$0.002Developer Utilities
Hexagonal pyramid calculator
volume and surface area from edge and height, free
POST /geom/hexagonal-pyramid$0.002Developer Utilities
Hyperbola calculator
foci, vertices, eccentricity, asymptote slopes
POST /geom/hyperbola$0.002Developer Utilities
Icosahedron calculator
volume and surface area from edge length, free
POST /geom/icosahedron$0.002Developer Utilities
Line equation from two points
slope-intercept and standard form, free
POST /geom/line-equation$0.002Developer Utilities
Midpoint calculator
center of a segment between two points
POST /geom/midpoint$0.002Developer Utilities
Oblique prism volume
Cavalieri from base area and perpendicular height
POST /geom/oblique-prism$0.002Developer Utilities
Octahedron calculator
volume, surface area, inradius and circumradius from edge
POST /geom/octahedron$0.002Developer Utilities
Parabola calculator
vertex, focus, directrix and axis, free
POST /geom/parabola$0.002Developer Utilities
Paraboloid volume calculator
volume of revolution from base radius and height
POST /geom/paraboloid$0.002Developer Utilities
Parallel or perpendicular lines
slopes, relation and angle
POST /geom/parallel-perpendicular$0.002Developer Utilities
Pentagonal prism calculator
volume and surface area from base edge and height
POST /geom/pentagonal-prism$0.002Developer Utilities
Point to line distance
perpendicular distance to ax+by+c=0
POST /geom/point-line-distance$0.002Developer Utilities
Polygon diagonals calculator
n(n−3)/2 for convex n-gons
POST /geom/polygon-diagonals$0.002Developer Utilities
Polygon perimeter from coordinates
sum edge lengths, free
POST /geom/polygon-perimeter$0.002Developer Utilities
Quadrilateral area calculator
shoelace formula from four vertices
POST /geom/quadrilateral-area$0.002Developer Utilities
Rectangular prism calculator
volume, surface area, diagonal, free
POST /geom/rectangular-prism$0.002Developer Utilities
Regular polygon calculator
area, perimeter, apothem, radius
POST /geom/regular-polygon$0.002Developer Utilities
Right triangle calculator
missing side, angles and area
POST /geom/right-triangle$0.002Developer Utilities
Section formula calculator
divide a segment in ratio m:n, free
POST /geom/section-formula$0.002Developer Utilities
Circular sector area and perimeter
radius and angle, free
POST /geom/sector-area$0.002Developer Utilities
Circular segment area
from radius and central angle
POST /geom/segment-area$0.002Developer Utilities
Sphere volume calculator
volume and surface area from radius or diameter
POST /geom/sphere-volume$0.002Developer Utilities
Spherical cap calculator
volume and curved surface area, free
POST /geom/spherical-cap$0.002Developer Utilities
Spherical sector calculator
volume and surface area from radius and cap height
POST /geom/spherical-sector$0.002Developer Utilities
Tank volume calculator
filled and total volume of horizontal or vertical cylindrical tanks
POST /geom/tank-volume$0.002Developer Utilities
Tetrahedron volume calculator
surface area, height and insphere from edge length
POST /geom/tetrahedron$0.002Developer Utilities
Trapezoid area calculator
bases, height, midsegment, free
POST /geom/trapezoid$0.002Developer Utilities
30-60-90 triangle calculator
sides and area from any one side
POST /geom/triangle-30-60-90$0.002Developer Utilities
AAS triangle calculator
two angles and a non-included side
POST /geom/triangle-aas$0.002Developer Utilities
Triangle area from coordinates
shoelace formula, free
POST /geom/triangle-area-coordinates$0.002Developer Utilities
ASA triangle calculator
two angles and included side, free
POST /geom/triangle-asa$0.002Developer Utilities
Triangle centroid calculator
average of three vertices
POST /geom/triangle-centroid$0.002Developer Utilities
Triangle orthocenter from coordinates
altitudes, free
POST /geom/triangle-orthocenter$0.002Developer Utilities
SAS triangle calculator
third side, area, angles from two sides and included angle
POST /geom/triangle-sas$0.002Developer Utilities
Triangular prism calculator
volume and surface area, free
POST /geom/triangular-prism$0.002Developer Utilities
Two circles intersection
find intersection points from centers and radii, free
POST /geom/two-circles-intersection$0.002Developer Utilities
Wedge volume calculator
rectangular wedge from base and two heights, free
POST /geom/wedge$0.002Developer Utilities
Anion gap calculator
serum AG and albumin correction, free
POST /health/anion-gap$0.002Developer Utilities
Blood pressure category calculator
ACC/AHA stages, free
POST /health/blood-pressure-category$0.002Developer Utilities
BMI Prime calculator
ratio to the 25 upper-normal threshold, free
POST /health/bmi-prime$0.002Developer Utilities
Harris-Benedict BMR calculator
basal metabolic rate from weight, height, age, sex
POST /health/bmr-harris-benedict$0.002Developer Utilities
Katch-McArdle BMR calculator
BMR from lean mass, free
POST /health/bmr-katch-mcardle$0.002Developer Utilities
Total body water calculator
Watson TBW volume and percentage, free
POST /health/body-water-percentage$0.002Developer Utilities
Body surface area Du Bois calculator
BSA from height and weight, free
POST /health/bsa-dubois$0.002Developer Utilities
Body surface area calculator
Mosteller formula BSA, free
POST /health/bsa-mosteller$0.002Developer Utilities
Calories burned calculator
MET, weight and duration, free estimate
POST /health/calories-burned$0.002Developer Utilities
Child and teen BMI calculator
BMI percentile and band, free
POST /health/child-bmi$0.002Developer Utilities
Corrected calcium calculator
albumin-adjusted serum calcium, free
POST /health/corrected-calcium$0.002Developer Utilities
Cycling calorie calculator
calories burned biking, free
POST /health/cycling-calories$0.002Developer Utilities
Fat-free mass index calculator
FFMI from weight, height and body fat, free
POST /health/fat-free-mass-index$0.002Developer Utilities
Daily fiber intake calculator
recommended grams from calories, free
POST /health/fiber-intake$0.002Developer Utilities
Mean arterial pressure calculator
MAP from systolic and diastolic, free
POST /health/mean-arterial-pressure$0.002Developer Utilities
Pack years calculator
cigarettes and years smoked, free
POST /health/pack-years$0.002Developer Utilities
Pregnancy weight gain calculator
BMI and weeks range, free
POST /health/pregnancy-weight-gain$0.002Developer Utilities
Daily protein intake calculator
grams from weight and g/kg target, free
POST /health/protein-intake$0.002Developer Utilities
Riegel race time predictor
predict finish times from a known race
POST /health/race-time-predictor$0.002Developer Utilities
Running calorie calculator
calories burned from distance, weight & grade
POST /health/running-calories$0.002Developer Utilities
Running pace calculator
min/km and min/mile from distance & time
POST /health/running-pace$0.002Developer Utilities
Steps to distance calculator
convert steps to km, miles, free
POST /health/steps-to-distance$0.002Developer Utilities
Swimming pace calculator
pace per 100m and 100 yards from distance & time
POST /health/swim-pace$0.002Developer Utilities
Target heart rate Karvonen calculator
reserve method, free
POST /health/target-hr-karvonen$0.002Developer Utilities
VO2 max Cooper test calculator
12-min distance estimate, free
POST /health/vo2max-cooper$0.002Developer Utilities
Waist-to-height ratio calculator
WHtR and risk category, free
POST /health/waist-height-ratio$0.002Developer Utilities
Waist-to-hip ratio calculator
WHR and health-risk band, free
POST /health/waist-hip-ratio$0.002Developer Utilities
BPM to milliseconds calculator
note durations & delay times, free
POST /hobby/bpm-to-ms$0.002Developer Utilities
Cents between frequencies calculator
musical interval in cents, free
POST /hobby/cents-interval$0.002Developer Utilities
Chord note calculator
notes and intervals from root and quality
POST /hobby/chord-notes$0.002Developer Utilities
Crop factor calculator
full-frame equivalent focal length & aperture, free
POST /hobby/crop-factor$0.002Developer Utilities
Depth of field calculator
near, far & total DOF, free
POST /hobby/depth-of-field$0.002Developer Utilities
Equivalent exposure calculator
match aperture, shutter & ISO, free
POST /hobby/equivalent-exposure$0.002Developer Utilities
Exposure value calculator
EV from aperture, shutter, ISO
POST /hobby/exposure-value$0.002Developer Utilities
Camera field of view calculator
AOV from focal length & sensor
POST /hobby/field-of-view$0.002Developer Utilities
Golden ratio font size calculator
heading & body type scale, free
POST /hobby/golden-ratio-type$0.002Developer Utilities
Knitting gauge calculator
cast on stitches & rows, free
POST /hobby/knitting-gauge$0.002Developer Utilities
Modular type scale generator
base, ratio & steps, free
POST /hobby/modular-scale$0.002Developer Utilities
Musical interval calculator
semitones and interval name from two notes, free
POST /hobby/musical-interval$0.002Developer Utilities
Note frequency calculator
equal temperament Hz from A4
POST /hobby/note-frequency$0.002Developer Utilities
NPF rule calculator
sharper max shutter for stars, free
POST /hobby/npf-rule$0.002Developer Utilities
Poker outs and odds calculator
next card and river hit probability, free
POST /hobby/poker-odds$0.002Developer Utilities
Print size & DPI calculator
pixels to inches, free
POST /hobby/print-dpi$0.002Developer Utilities
Reading time estimator
word count and WPM to duration, free
POST /hobby/reading-time$0.002Developer Utilities
Epoxy resin mix calculator
resin & hardener amounts by ratio, free
POST /hobby/resin-mix$0.002Developer Utilities
Musical scale generator
notes from root and scale type, free
POST /hobby/scale-notes$0.002Developer Utilities
Music transposition calculator
notes and chords by semitones
POST /hobby/transpose$0.002Developer Utilities
Yarn weight substitution calculator
skeins to buy from yardage, free
POST /hobby/yarn-substitution$0.002Developer Utilities
Air conditioner BTU calculator
room cooling capacity, free
POST /home/ac-btu$0.002Developer Utilities
Concrete block calculator
blocks from wall area, face size and waste
POST /home/blocks$0.002Developer Utilities
Carpet calculator
linear metres and area from room size and roll width free
POST /home/carpet$0.002Developer Utilities
Concrete column calculator
cylindrical volume from diameter, height and count
POST /home/concrete-column$0.002Developer Utilities
Concrete footing calculator
volume from L×W×D×count, free
POST /home/concrete-footing$0.002Developer Utilities
Concrete slab calculator
volume and bags from length, width, thickness free
POST /home/concrete-slab$0.002Developer Utilities
Crown molding calculator
sticks from perimeter and waste, free
POST /home/crown-molding$0.002Developer Utilities
Deck board calculator
boards needed from area, size, gap and waste free
POST /home/deck-boards$0.002Developer Utilities
Fence post calculator
posts and rails from length and spacing, free
POST /home/fence-posts$0.002Developer Utilities
Lawn fertilizer calculator
pounds to apply from area, N rate, and bag nitrogen % free
POST /home/fertilizer$0.002Developer Utilities
Floor tile calculator
tiles and boxes from room area, size and waste free
POST /home/floor-tiles$0.002Developer Utilities
Gravel calculator
volume and weight from area, depth and density, free
POST /home/gravel$0.002Developer Utilities
Heater BTU calculator
room volume, insulation and temperature rise free
POST /home/heater-btu$0.002Developer Utilities
Insulation R-value calculator
total assembly R and U-factor from layers
POST /home/insulation$0.002Developer Utilities
Laminate flooring calculator
packs from room area, coverage and waste
POST /home/laminate-flooring$0.002Developer Utilities
Mortar calculator
volume and bags from brick or block count free
POST /home/mortar$0.002Developer Utilities
Paver calculator
patio pavers needed from area, size and waste free
POST /home/pavers$0.002Developer Utilities
Pool chlorine dosage calculator
dose from volume, free chlorine levels, and product strength free
POST /home/pool-chlorine$0.002Developer Utilities
Swimming pool volume calculator
liters and gallons from shape and dimensions
POST /home/pool-volume$0.002Developer Utilities
Roof pitch calculator
rise, run, slope angle and rafter factor, free
POST /home/roof-pitch$0.002Developer Utilities
Roofing shingles calculator
bundles and squares from area and pitch free
POST /home/roof-shingles$0.002Developer Utilities
Sand calculator
volume and weight from area, depth and density
POST /home/sand$0.002Developer Utilities
Staircase step calculator
riser count, exact riser and tread run
POST /home/staircase-steps$0.002Developer Utilities
Topsoil calculator
volume in cubic yards and cubic meters from area and depth free
POST /home/topsoil$0.002Developer Utilities
Wall stud calculator
count studs from length, spacing and openings
POST /home/wall-studs$0.002Developer Utilities
Wall tile calculator
tiles and boxes from area, size and waste
POST /home/wall-tiles$0.002Developer Utilities
Wallpaper rolls calculator
pattern repeat included, free
POST /home/wallpaper-rolls$0.002Developer Utilities
Water tank volume calculator
capacity in liters and gallons at a fill depth, free
POST /home/water-tank-volume$0.002Developer Utilities
Buy one get one discount calculator
BOGO effective % free
POST /life/bogo-discount$0.002Developer Utilities
Recipe cost per serving calculator
ingredient costs ÷ servings, free
POST /life/cost-per-serving$0.002Developer Utilities
Shared expense splitter
itemized costs by weight free
POST /life/expense-split$0.002Developer Utilities
Quit a habit savings calculator
money saved by quitting free
POST /life/habit-savings$0.002Developer Utilities
Markup to margin converter
selling price, free
POST /life/markup-margin$0.002Developer Utilities
Overtime pay calculator
hourly rate, OT hours, gross pay, free
POST /life/overtime-pay$0.002Developer Utilities
Price per 100g calculator
compare products, find cheapest, free
POST /life/price-per-100g$0.002Developer Utilities
Rule of 114 and 144 calculator
years to triple or quadruple free
POST /life/rule-of-114$0.002Developer Utilities
Salary to hourly converter
annual pay to hourly wage free
POST /life/salary-to-hourly$0.002Developer Utilities
Sales tax calculator
tax amount and total from rate, free
POST /life/sales-tax$0.002Developer Utilities
Savings goal time calculator
months to target with fixed deposits
POST /life/savings-goal-time$0.002Developer Utilities
Subscription annual cost calculator
monthly & yearly totals, free
POST /life/subscription-annual$0.002Developer Utilities
Tip and split calculator
bill, tip %, per person, free
POST /life/tip-split$0.002Developer Utilities
Unit price comparison calculator
price per unit and best value, free
POST /life/unit-price$0.002Developer Utilities
Arithmetic sequence calculator
nth term and partial sum, free
POST /math/arithmetic-sequence$0.002Developer Utilities
Arithmetic series sum calculator
S = n(a1+an)/2, free
POST /math/arithmetic-series-sum$0.002Developer Utilities
Catalan number calculator
nth Catalan C(n), free
POST /math/catalan-number$0.002Developer Utilities
Double factorial calculator
compute n!! with BigInt precision
POST /math/double-factorial$0.002Developer Utilities
Factorial calculator
n! exact BigInt product, free
POST /math/factorial-calculator$0.002Developer Utilities
Fibonacci number calculator
nth term and sequence, free
POST /math/fibonacci$0.002Developer Utilities
Sum of Fibonacci series
first n terms equal F(n+2)−1
POST /math/fibonacci-sum$0.002Developer Utilities
Infinite geometric series sum
S = a/(1−r), free calculator
POST /math/geometric-series-sum$0.002Developer Utilities
Hexagonal number calculator
H(n)=n(2n−1) and membership test, free
POST /math/hexagonal-number$0.002Developer Utilities
Look-and-say sequence
n-th term from a seed by run-length
POST /math/look-and-say$0.002Developer Utilities
Padovan sequence calculator
n-th Padovan number P(n)
POST /math/padovan-number$0.002Developer Utilities
Pentagonal number calculator
P(n)=n(3n−1)/2 and membership test
POST /math/pentagonal-number$0.002Developer Utilities
Polygonal number calculator
n-th s-gonal figurate number
POST /math/polygonal-number$0.002Developer Utilities
Primorial calculator
n# product of primes ≤ n, free
POST /math/primorial$0.002Developer Utilities
Square pyramidal number
sum of first n squares n(n+1)(2n+1)/6
POST /math/pyramidal-number$0.002Developer Utilities
Stern diatomic / Stern-Brocot sequence
n-th term s(n)
POST /math/stern-brocot$0.002Developer Utilities
Sum of first n even numbers
2+4+…+2n = n(n+1)
POST /math/sum-of-even$0.002Developer Utilities
Sum of first n odd numbers
equals n squared, free calculator
POST /math/sum-of-odd$0.002Developer Utilities
Sum of first n squares
1²+2²+…+n² = n(n+1)(2n+1)/6
POST /math/sum-of-squares$0.002Developer Utilities
Sylvester sequence calculator
nth term with BigInt, free
POST /math/sylvester-sequence$0.002Developer Utilities
Angular velocity calculator
ω from angle & time or RPM, free
POST /mech/angular-velocity$0.002Developer Utilities
Atwood machine calculator
acceleration & tension, free in browser
POST /mech/atwood-machine$0.002Developer Utilities
Average velocity calculator
displacement over time in m/s and km/h free
POST /mech/average-velocity$0.002Developer Utilities
Banked curve calculator
ideal banking angle from radius and speed
POST /mech/banked-curve$0.002Developer Utilities
Centripetal acceleration calculator
a = v²/r from speed and radius free
POST /mech/centripetal-acceleration$0.002Developer Utilities
Centripetal force calculator
F=mv²/r from mass, speed, and radius
POST /mech/centripetal-force$0.002Developer Utilities
Coefficient of friction calculator
μ = Ff / N, free in browser
POST /mech/coefficient-of-friction$0.002Developer Utilities
Elastic collision calculator
final velocities of two masses in 1D free
POST /mech/elastic-collision$0.002Developer Utilities
Force calculator
F=ma from mass and acceleration (or solve mass/accel)
POST /mech/force-mass-accel$0.002Developer Utilities
Free fall calculator
fall time and impact velocity from rest
POST /mech/free-fall$0.002Developer Utilities
Hooke's law calculator
spring force F=kx (or solve k or x)
POST /mech/hookes-law$0.002Developer Utilities
Horizontal projectile motion calculator
fall time, range and impact velocity free
POST /mech/horizontal-projectile$0.002Developer Utilities
Impulse calculator
impulse and Δp from force and contact time
POST /mech/impulse$0.002Developer Utilities
Inclined plane calculator
acceleration and normal force free
POST /mech/inclined-plane$0.002Developer Utilities
Kinematics distance calculator
displacement from velocity, acceleration, time
POST /mech/kinematics-distance$0.002Developer Utilities
Final velocity calculator
v = u + at, free in browser
POST /mech/kinematics-velocity$0.002Developer Utilities
Kinetic energy calculator
KE = ½mv², free in browser
POST /mech/kinetic-energy$0.002Developer Utilities
Moment of inertia calculator
ring, disc, sphere, rod, free
POST /mech/moment-of-inertia$0.002Developer Utilities
Momentum calculator
linear momentum p=mv in kg·m/s free
POST /mech/momentum$0.002Developer Utilities
Newton's second law calculator
F = ma, free in browser
POST /mech/newton-second-law$0.002Developer Utilities
Pendulum length calculator
required length from period and g free
POST /mech/pendulum-length$0.002Developer Utilities
Power calculator
mechanical power in watts and horsepower from work and time
POST /mech/power$0.002Developer Utilities
Power from force and velocity
P=Fv in watts free
POST /mech/power-force-velocity$0.002Developer Utilities
Projectile from height calculator
range and flight time above ground
POST /mech/projectile-launch-from-height$0.002Developer Utilities
Pulley mechanical advantage calculator
ideal IMA and effort force free
POST /mech/pulley-mechanical-advantage$0.002Developer Utilities
Rotational kinetic energy calculator
KE=½Iω² in joules free
POST /mech/rotational-kinetic-energy$0.002Developer Utilities
Spring constant calculator
k = F/x, free in browser
POST /mech/spring-constant$0.002Developer Utilities
Terminal velocity calculator
mass, drag, density and area free
POST /mech/terminal-velocity$0.002Developer Utilities
Torque calculator
τ = rF sin(θ) in newton-metres
POST /mech/torque$0.002Developer Utilities
Work done calculator
W=Fd cos θ in joules free
POST /mech/work-done$0.002Developer Utilities
Aliquot sum calculator
proper divisors, perfect / deficient / abundant
POST /numth/aliquot-sum$0.002Developer Utilities
Amicable numbers checker
test if two integers form an amicable pair
POST /numth/amicable-numbers$0.002Developer Utilities
Armstrong number checker
narcissistic numbers, digit power sum
POST /numth/armstrong-number$0.002Developer Utilities
Automorphic number checker
does n² end with n, free
POST /numth/automorphic-number$0.002Developer Utilities
Digit sum calculator
sum digits in any base, free
POST /numth/digit-sum$0.002Developer Utilities
Digital root calculator
repeated digit sum and additive persistence
POST /numth/digital-root$0.002Developer Utilities
Number of divisors calculator
tau(n) from prime factors
POST /numth/divisor-count$0.002Developer Utilities
Sum of divisors calculator
sigma(n) from prime factors
POST /numth/divisor-sum$0.002Developer Utilities
Euler's totient φ(n)
count coprimes from prime factors
POST /numth/euler-totient$0.002Developer Utilities
Extended Euclidean calculator
gcd and Bézout coefficients x, y
POST /numth/extended-euclidean$0.002Developer Utilities
Factorial prime factorization
n! factors via Legendre formula
POST /numth/factorial-prime-factors$0.002Developer Utilities
Happy number checker
sum of squares of digits until 1 or a cycle
POST /numth/happy-number$0.002Developer Utilities
Jacobi symbol calculator
(a/n) via quadratic reciprocity
POST /numth/jacobi-symbol$0.002Developer Utilities
Legendre symbol (a/p)
quadratic residuosity mod odd prime
POST /numth/legendre-symbol$0.002Developer Utilities
Mersenne number checker
compute 2^p−1 and Lucas-Lehmer primality
POST /numth/mersenne-number$0.002Developer Utilities
Modular exponentiation calculator
base^exp mod m (fast BigInt)
POST /numth/modular-exponentiation$0.002Developer Utilities
Modular multiplicative inverse
a⁻¹ mod m via extended Euclidean
POST /numth/modular-inverse$0.002Developer Utilities
Next prime after n
smallest prime strictly greater than n
POST /numth/next-prime$0.002Developer Utilities
Pandigital number checker
each base digit once, missing digits
POST /numth/pandigital-checker$0.002Developer Utilities
Previous prime finder
largest prime strictly less than n
POST /numth/prev-prime$0.002Developer Utilities
Prime counting function π(n)
count primes ≤ n by sieve
POST /numth/prime-counting$0.002Developer Utilities
Quadratic residue checker
is a a square mod m, list residues
POST /numth/quadratic-residue$0.002Developer Utilities
Radix converter
change integer bases 2–36, free
POST /numth/radix-convert$0.002Developer Utilities
Factorial trailing zeros
count zeros of n! via powers of five
POST /numth/trailing-zeros-factorial$0.002Developer Utilities
Twin prime checker
test (n, n+2) and list pairs up to a limit
POST /numth/twin-primes$0.002Developer Utilities
Brewster angle calculator
polarization angle from n₁, n₂, free
POST /optics/brewster-angle$0.002Developer Utilities
Critical angle calculator
total internal reflection from two indices
POST /optics/critical-angle$0.002Developer Utilities
Diffraction grating calculator
angle from d, λ, order m, free
POST /optics/diffraction-grating$0.002Developer Utilities
F-stop calculator
f-number from focal length and aperture diameter, free
POST /optics/f-number$0.002Developer Utilities
Lens magnification calculator
linear m = −v/u for lenses and mirrors, free
POST /optics/lens-magnification$0.002Developer Utilities
Lens power calculator
diopters from focal length (m), free
POST /optics/lens-power$0.002Developer Utilities
Mirror equation calculator
image distance & magnification from f and do
POST /optics/mirror-equation$0.002Developer Utilities
Single-slit diffraction calculator
angular position of minima from a, λ and order m, free
POST /optics/single-slit-diffraction$0.002Developer Utilities
Snell's law calculator
refraction angle from n1, n2 and incidence, free
POST /optics/snell-law$0.002Developer Utilities
Telescope magnification calculator
angular M from objective & eyepiece
POST /optics/telescope-magnification$0.002Developer Utilities
Beat frequency calculator
f_beat = |f1 − f2| free, rejects negative Hz
POST /phys/beat-frequency$0.002Developer Utilities
Doppler effect calculator
observed frequency and frequency shift, free
POST /phys/doppler-effect$0.002Developer Utilities
Doppler shift sound calculator
perceived frequency from relative speed
POST /phys/doppler-sound$0.002Developer Utilities
Period to frequency calculator
convert T↔f (Hz) free, rejects zero
POST /phys/period-frequency$0.002Developer Utilities
Pipe resonance calculator
open/closed pipe fundamental and harmonics
POST /phys/pipe-resonance$0.002Developer Utilities
Sound intensity calculator
I = P / (4πr²) in W/m², free
POST /phys/sound-intensity$0.002Developer Utilities
Decibel calculator
sound intensity level L=10·log₁₀(I/I₀) free, rejects non-positive I
POST /phys/sound-intensity-db$0.002Developer Utilities
Speed of sound calculator
dry air from temperature (m/s)
POST /phys/speed-of-sound-air$0.002Developer Utilities
Standing wave calculator
nodes and wavelength from harmonic number and string length, free
POST /phys/standing-wave$0.002Developer Utilities
Wave speed on a string calculator
v = √(T/μ), free
POST /phys/wave-on-string-speed$0.002Developer Utilities
Wave speed calculator
v=fλ from frequency and wavelength (or solve any)
POST /phys/wave-speed$0.002Developer Utilities
Birthday paradox calculator
shared day probability for n people
POST /prob/birthday-paradox$0.002Developer Utilities
Coin flip probability
exactly k heads in n flips, free
POST /prob/coin-flip$0.002Developer Utilities
Conditional probability calculator
P(A|B) and independence test
POST /prob/conditional-probability$0.002Developer Utilities
Dice sum probability
every total for k dice with s sides
POST /prob/dice-sum$0.002Developer Utilities
Dice roll probability
exact or at-least target sum with k s-sided dice
POST /prob/dice-target$0.002Developer Utilities
Expected value calculator
mean, variance and standard deviation
POST /prob/expected-value$0.002Developer Utilities
Geometric distribution calculator
P(first success on trial k) and E[X]
POST /prob/geometric-distribution$0.002Developer Utilities
Hypergeometric probability
k successes in n draws, free
POST /prob/hypergeometric$0.002Developer Utilities
Odds to probability converter
a to b, percent, free
POST /prob/odds-converter$0.002Developer Utilities
Poisson probability calculator
P(X=k), CDF, mean and variance
POST /prob/poisson-distribution$0.002Developer Utilities
Poker hand odds
exact pair, flush, full house probability
POST /prob/poker-odds$0.002Developer Utilities
Beam deflection calculator
simply supported max δ = PL³/(48EI)
POST /sci/beam-deflection$0.002Developer Utilities
Bending stress calculator
σ = My/I elastic flexure formula
POST /sci/bending-stress$0.002Developer Utilities
Gear ratio calculator
teeth counts to GR and output speed, free
POST /sci/gear-ratio$0.002Developer Utilities
Shear stress calculator
τ = F/A in pascals, free
POST /sci/shear-stress$0.002Developer Utilities
Stress calculator
mechanical stress σ = F/A in pascals and megapascals, free
POST /sci/stress$0.002Developer Utilities
Thermal stress calculator
constrained bar σ = E·α·ΔT in Pa and MPa, free
POST /sci/thermal-stress$0.002Developer Utilities
Young's modulus calculator
elasticity E = σ/ε, solve stress, strain or E, free
POST /sci/youngs-modulus$0.002Developer Utilities
Coefficient of variation calculator
CV ratio and percentage from a list
POST /stat/coefficient-variation$0.002Developer Utilities
Five-number summary calculator
min, Q1, median, Q3, max of a data set, free
POST /stat/five-number-summary$0.002Developer Utilities
Geometric mean calculator
n-th root of the product of positive numbers, free
POST /stat/geometric-mean$0.002Developer Utilities
Harmonic mean calculator
reciprocal average of positive numbers
POST /stat/harmonic-mean$0.002Developer Utilities
Linear regression calculator
least-squares slope, intercept and R², free
POST /stat/linear-regression$0.002Developer Utilities
Mean median mode calculator
average, mid value, most common, range
POST /stat/mean-median-mode$0.002Developer Utilities
Quartile and IQR calculator
Q1 Q2 Q3, range and outlier fences
POST /stat/quartiles$0.002Developer Utilities
Skewness and kurtosis calculator
sample shape of a data set
POST /stat/skewness-kurtosis$0.002Developer Utilities
Variance calculator
population and sample variance with mean
POST /stat/variance$0.002Developer Utilities
Weighted average calculator
mean of values with weights
POST /stat/weighted-mean$0.002Developer Utilities
Z-score calculator
standardize values with mean and standard deviation, free
POST /stat/z-score$0.002Developer Utilities
Remove duplicate lines
keep first occurrences, free online
POST /str/dedupe-lines$0.002Developer Utilities
Convert to dot.case
turn any phrase into dot.case, free
POST /str/dot-case$0.002Developer Utilities
List unique words
extract word list in order, free
POST /str/extract-unique-words$0.002Developer Utilities
Find and replace text
swap every match, free online
POST /str/find-replace$0.002Developer Utilities
Kebab-case converter
lowercase words joined with hyphens, free
POST /str/kebab-case$0.002Developer Utilities
Count lines
total, non-empty and blank, free
POST /str/line-count$0.002Developer Utilities
Convert to lowercase
turn any text into lower case letters, free
POST /str/lowercase$0.002Developer Utilities
Add line numbers to text
sequential numbering, free online
POST /str/number-lines$0.002Developer Utilities
Pad text
fill a string to a target width left, right, or both sides, free
POST /str/pad$0.002Developer Utilities
Count paragraphs
blank-line paragraph counter, free
POST /str/paragraph-count$0.002Developer Utilities
PascalCase converter
convert text to PascalCase, free
POST /str/pascal-case$0.002Developer Utilities
Remove accents from text
strip diacritics to plain ASCII letters, free
POST /str/remove-accents$0.002Developer Utilities
Remove line breaks from text
join to a single line (optional space), free
POST /str/remove-line-breaks$0.002Developer Utilities
Remove extra spaces
collapse repeated spaces and trim, free
POST /str/remove-spaces$0.002Developer Utilities
Reverse text
flip character order, Unicode-safe, free
POST /str/reverse$0.002Developer Utilities
Reverse word order
flip words, keep each word intact, free
POST /str/reverse-words$0.002Developer Utilities
Sentence case converter
capitalize sentences, free
POST /str/sentence-case$0.002Developer Utilities
Sentence counter
count sentences in text free
POST /str/sentence-count$0.002Developer Utilities
Convert to snake_case
turn any phrase into snake_case, free
POST /str/snake-case$0.002Developer Utilities
Sort lines alphabetically
A–Z or Z–A, free online
POST /str/sort-lines$0.002Developer Utilities
Title case converter
capitalize words with small-word rules, free
POST /str/title-case$0.002Developer Utilities
Trim whitespace from every line
strip leading and trailing spaces, free
POST /str/trim-lines$0.002Developer Utilities
Truncate text
max length with ellipsis, optional word boundary, free
POST /str/truncate$0.002Developer Utilities
Word & character counter
count words, sentences, paragraphs free
POST /str/word-count$0.002Developer Utilities
Area thermal expansion calculator
ΔA = A₀·α·ΔT free
POST /thermo/area-expansion$0.002Developer Utilities
Bernoulli equation calculator
unknown pressure from density, speed, height, free
POST /thermo/bernoulli-pressure$0.002Developer Utilities
Boyle's law calculator
find final P or V from P1·V1=P2·V2 at constant T, free
POST /thermo/boyles-law$0.002Developer Utilities
Buoyancy calculator
F_b = ρ V g (Archimedes), free
POST /thermo/buoyant-force$0.002Developer Utilities
Celsius to Fahrenheit calculator
convert C↔F free online
POST /thermo/celsius-fahrenheit$0.002Developer Utilities
Pipe flow continuity calculator
outlet speed from A1·v1=A2·v2, free
POST /thermo/continuity-equation$0.002Developer Utilities
Partial pressure calculator
Dalton's law Pi=yi·P, free
POST /thermo/dalton-partial-pressure$0.002Developer Utilities
Entropy change calculator
ΔS = Q/T from heat transferred and absolute temperature, free
POST /thermo/entropy-change$0.002Developer Utilities
Mixing temperature calculator
equilibrium after mixing two masses, free
POST /thermo/final-temperature-mixing$0.002Developer Utilities
Gas density calculator
ideal gas ρ = PM/RT from pressure, molar mass and T, free
POST /thermo/gas-density$0.002Developer Utilities
Molar volume calculator
ideal gas Vm = RT/P from pressure and temperature, free
POST /thermo/gas-molar-volume$0.002Developer Utilities
Gay-Lussac law calculator
P/T at constant volume, free
POST /thermo/gay-lussac-law$0.002Developer Utilities
Specific heat calculator
heat energy Q=mcΔT in joules
POST /thermo/heat-energy$0.002Developer Utilities
Hydrostatic pressure calculator
P = ρ·g·h with optional atmospheric offset, free
POST /thermo/hydrostatic-pressure$0.002Developer Utilities
Ideal gas law calculator
solve PV = nRT for P, V, n, or T, free
POST /thermo/ideal-gas-law$0.002Developer Utilities
Isothermal work calculator
ideal-gas W=nRT ln(V2/V1), free
POST /thermo/isothermal-work$0.002Developer Utilities
Kelvin converter
Celsius, Fahrenheit and Kelvin together, free
POST /thermo/kelvin-converter$0.002Developer Utilities
Linear thermal expansion calculator
ΔL = L₀·α·ΔT from length, coefficient and temperature change, free
POST /thermo/linear-expansion$0.002Developer Utilities
Newton's law of cooling calculator
T(t) from Ta, T0, k, t, free
POST /thermo/newton-cooling$0.002Developer Utilities
Pressure calculator
P=F/A in Pa, bar and psi, free
POST /thermo/pressure-force-area$0.002Developer Utilities
Relative humidity calculator
RH from actual and saturation vapor pressure, free
POST /thermo/relative-humidity$0.002Developer Utilities
Reynolds number calculator
Re=ρVL/μ, free
POST /thermo/reynolds-number$0.002Developer Utilities
Specific heat capacity calculator
c = Q/(m·ΔT) from heat, mass and temperature change, free
POST /thermo/specific-heat-capacity$0.002Developer Utilities
Heat conduction calculator
Q = k A ΔT / L through a wall, free
POST /thermo/thermal-conduction$0.002Developer Utilities
Thermal efficiency calculator
η = (W/Q_in)×100% from work output and heat input, free
POST /thermo/thermal-efficiency$0.002Developer Utilities
Arrival local time calculator
flight duration + UTC offsets, free
POST /travel/arrival-local-time$0.002Developer Utilities
Average speed calculator
total distance over elapsed time free
POST /travel/average-speed$0.002Developer Utilities
Travel points value calculator
cents per point vs baseline, free
POST /travel/award-value$0.002Developer Utilities
Cycling time estimator
bike ride duration from distance and speed, free
POST /travel/cycling-time$0.002Developer Utilities
Travel distance unit converter
kilometers, miles and nautical miles, free
POST /travel/distance-unit-convert$0.002Developer Utilities
ETA calculator
estimated arrival clock time from departure, free
POST /travel/eta-calculator$0.002Developer Utilities
MPG to L/100km converter
US MPG, imperial MPG and liters per 100 km, free
POST /travel/fuel-economy-convert$0.002Developer Utilities
Luggage linear inches calculator
L+W+H and airline limit check, free
POST /travel/luggage-linear-inches$0.002Developer Utilities
Luggage volume calculator
bag liters and cubic inches from L×W×H, free
POST /travel/luggage-volume$0.002Developer Utilities
Airline miles value calculator
cents per point from cash fare and taxes, free
POST /travel/miles-to-points$0.002Developer Utilities
Driving range remaining calculator
fuel or charge × economy, free
POST /travel/range-remaining$0.002Developer Utilities
Road trip time calculator
driving time and arrival offset, free
POST /travel/road-trip-time$0.002Developer Utilities
Speed unit converter
km/h, mph, knots, m/s, free
POST /travel/speed-unit-convert$0.002Developer Utilities
Timezone offset difference
hours between two UTC offsets, free
POST /travel/timezone-offset-diff$0.002Developer Utilities
Tire pressure by load calculator
adjust PSI for actual load, free
POST /travel/tire-pressure-load$0.002Developer Utilities
Road trip cost split
fuel and tolls per passenger free
POST /travel/trip-cost-split$0.002Developer Utilities
Trip fuel cost estimator
distance, MPG and fuel price, free
POST /travel/trip-fuel-cost$0.002Developer Utilities
Walking time estimator
distance and pace to duration, free
POST /travel/walking-time$0.002Developer Utilities
Amplitude, period & phase shift calculator
from A sin(Bx+C)+D
POST /trig/amplitude-period$0.002Developer Utilities
Angle of elevation calculator
distance and height to angle, free
POST /trig/angle-of-elevation$0.002Developer Utilities
Coterminal angle calculator
positive and negative within one turn
POST /trig/coterminal-angle$0.002Developer Utilities
Degrees minutes seconds converter
DMS ↔ decimal degrees either way
POST /trig/dms-to-decimal$0.002Developer Utilities
Double-angle calculator
sin(2x), cos(2x), tan(2x) from one angle
POST /trig/double-angle$0.002Developer Utilities
Arccosine calculator
acos(x) in degrees and radians, free
POST /trig/inverse-cos$0.002Developer Utilities
Arctangent calculator
atan and atan2 in degrees and radians
POST /trig/inverse-tan$0.002Developer Utilities
Law of cosines angle finder
three sides to all angles, free
POST /trig/law-of-cosines-angle$0.002Developer Utilities
Law of sines calculator
missing side or angle from a pair
POST /trig/law-of-sines$0.002Developer Utilities
Polar to rectangular converter
r and θ to cartesian x, y
POST /trig/polar-to-rectangular$0.002Developer Utilities
Reference angle calculator
degrees or radians, quadrant, free
POST /trig/reference-angle$0.002Developer Utilities
Right triangle trig solver
one side and acute angle, free
POST /trig/right-triangle-trig$0.002Developer Utilities
Sine cosine tangent calculator
sin, cos, tan, csc, sec, cot from an angle
POST /trig/sin-cos-tan$0.002Developer Utilities
Sine wave calculator
amplitude, period, phase, vertical shift, value at x
POST /trig/sine-wave$0.002Developer Utilities
Sum and difference angle calculator
sin cos tan of a±b, free
POST /trig/sum-difference$0.002Developer Utilities
Exact trig values calculator
sin cos tan radicals for special angles, free
POST /trig/trig-exact-values$0.002Developer Utilities
Miles to km converter
convert miles to kilometers, free
POST /conv/miles-to-km$0.002Developer Utilities
Bearing and heading calculator
compass direction between two points
POST /trig/bearing$0.002Developer Utilities
Feet to cm converter
convert feet to centimeters, free
POST /conv/feet-to-cm$0.002Developer Utilities
Triangular number calculator
n-th triangle and membership test
POST /math/triangular-number$0.002Developer Utilities
Harshad number checker
Niven test and quotient, free
POST /numth/harshad-number$0.002Developer Utilities
Rate constant from rate law calculator
k from measured rate, free
POST /chem/rate-constant-from-rate$0.002Developer Utilities
PEM Base64 encoder
64-char lines with BEGIN/END headers, free
POST /enc/base64-pem$0.002Developer Utilities
Absence percentage calculator
days absent over scheduled workdays
POST /fin/absence-percentage$0.002Developer Utilities
AAA triangle calculator
three angles and one side via law of sines
POST /math/aaa-triangle$0.002Developer Utilities
Absolute humidity calculator
grams of water vapor per cubic meter, free
POST /phys/absolute-humidity$0.002