ForHosting KIT · Developer Utilities

Paint quantity calculator

This paint quantity calculator turns wall area or simple room dimensions into the litres of paint you should buy for a given number of coats and a manufacturer coverage rate.

● BetaFree · in your browser

Run — free How it works & API

Use it from WebAPIEmailTelegramApp soon

Homeowners, landlords, and contractors routinely under-order by forgetting second coats or over-order when they ignore doors and windows; the arithmetic itself is small but easy to get wrong under time pressure. The engine accepts either a total paintable surface in square metres or length, width, and height so it can form four-wall area as two times the sum of length and width times height. Optional openings subtract door and window voids so you do not paint glass. Coverage is the spread rate printed on the tin in square metres per litre, and coats multiplies the surface once for each layer. The response returns gross and net area, exact litres, and a whole-litre ceiling for shopping, with no network calls and fully deterministic floating-point math. Use it free in the browser before a store run, or call the API at $0.002 per successful request when estimating fleets of rooms in quoting tools, renovation planners, or CI fixtures that must not invent stock levels.

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

POSThttps://api.kit.forhosting.com/home/paint-needed

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/home/paint-needed \
  -H "Authorization: Bearer $KIT_KEY" \
  -H "Content-Type: application/json" \
  -d '{"coats":2,"coverage":10,"area":48}'

const res = await fetch("https://api.kit.forhosting.com/home/paint-needed", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.KIT_KEY}`,
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "coats": 2,
    "coverage": 10,
    "area": 48
  })
});
const { task_id } = await res.json();

import os, requests

res = requests.post(
    "https://api.kit.forhosting.com/home/paint-needed",
    headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
    json={
    "coats": 2,
    "coverage": 10,
    "area": 48
},
)
task_id = res.json()["task_id"]

<?php
$res = file_get_contents("https://api.kit.forhosting.com/home/paint-needed", false, stream_context_create([
  "http" => [
    "method"  => "POST",
    "header"  => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
    "content" => '{"coats":2,"coverage":10,"area":48}',
  ],
]));
$task = json_decode($res, true);

body := bytes.NewBufferString(`{"coats":2,"coverage":10,"area":48}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/home/paint-needed", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)

Example request

{
  "coats": 2,
  "coverage": 10,
  "area": 48
}

Example response

{
  "task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
  "type": "home.paint_needed",
  "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

Per request$0.002

Published price — no tokens, no invented credits. A failed task is never charged.

Limits

max_abs 1000000000

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.

Read the full KIT documentation →

Run — free