Regular polygon calculator
A regular polygon has equal sides and equal interior angles. Once you fix the number of sides and the common side length, every classical metric is determined: the perimeter is simply the product of those two numbers, each interior angle follows from the regular n-gon formula, the apothem is the distance from the center to the midpoint of a side, the circumradius is the distance from the center to a vertex, and the area can be written with side length and the tangent of half the central angle. Students need these numbers for homework on hexagons, octagons, and other regular figures; makers and engineers need them when a bolt pattern, tile, or frame is specified by side count and edge length alone. This capacity accepts integer sides of three or more and a positive side length, rejects digons and monogons, and returns perimeter, interior angle, apothem, circumradius, and area as structured JSON. The same pure function powers the free browser widget and the prepaid API path, so a golden server example matches what a visitor runs locally with no network round trip and no language-model involvement.
Run — free
Runs in your browser. Free, unlimited — your data never leaves this page.
How to use it
Enter your values in the form above. The tool checks them before calculating and shows the result on the same page.
Check your inputs
Use the labels and units shown next to each field. If something is missing or outside the allowed range, the page points to the field to fix.
Use it again or automate it
Use the browser tool for individual checks and the API when you need the same capability in an automated workflow.
What you can do with it
Get an answer now
Enter one set of values and see the result without building a spreadsheet or script.
Compare scenarios
Change one value at a time and rerun the calculation to understand what affects the result.
Automate repeated work
Use the API when the same calculation needs to run inside your product or workflow.
FAQ
How do I use this capability?
Complete the fields above and run it on this page. The form highlights anything that needs attention.
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/geom/regular-polygon \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"sides":6,"side_length":2}'const res = await fetch("https://api.kit.forhosting.com/geom/regular-polygon", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"sides": 6,
"side_length": 2
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/geom/regular-polygon",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"sides": 6,
"side_length": 2
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/geom/regular-polygon", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"sides":6,"side_length":2}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"sides":6,"side_length":2}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/geom/regular-polygon", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"sides": 6,
"side_length": 2
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "geom.regular_polygon",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |