ForHosting KIT · Developer Utilities

Waist-to-height ratio calculator

Waist-to-height ratio calculator: enter your values and see a clear result on this page. Free for individual checks; API from $0.002.

● BetaFree · in your browser

Run — free How it works & API

Use it from WebAPIEmailTelegramApp soon

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

What is waist-to-height ratio?

WHtR is waist circumference divided by standing height using the same linear units. It is a simple central-adiposity index; many guides recommend keeping the ratio below 0.5 (waist less than half of height).

What happens if height is zero or negative?

The request fails with invalid_input. Height must be strictly greater than zero because a zero height makes the ratio undefined and a negative height is non-physical.

How are risk categories assigned?

Ashwell-style bands: underweight below 0.40, healthy from 0.40 up to below 0.50, increased from 0.50 up to below 0.60, and high at or above 0.60. Labels are educational screening categories, not a clinical diagnosis.

Do waist and height need the same units?

Yes. Both must use the same linear unit (for example both cm or both inches). The ratio is unitless, but mixed units would produce a meaningless number.

What does it cost?

The browser tool is free and runs locally. API requests use prepaid KIT balance at $0.002 per successful item; invalid input is not charged.

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/health/waist-height-ratio

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/health/waist-height-ratio \
  -H "Authorization: Bearer $KIT_KEY" \
  -H "Content-Type: application/json" \
  -d '{"waist":80,"height":170}'

const res = await fetch("https://api.kit.forhosting.com/health/waist-height-ratio", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.KIT_KEY}`,
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "waist": 80,
    "height": 170
  })
});
const { task_id } = await res.json();

import os, requests

res = requests.post(
    "https://api.kit.forhosting.com/health/waist-height-ratio",
    headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
    json={
    "waist": 80,
    "height": 170
},
)
task_id = res.json()["task_id"]

<?php
$res = file_get_contents("https://api.kit.forhosting.com/health/waist-height-ratio", false, stream_context_create([
  "http" => [
    "method"  => "POST",
    "header"  => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
    "content" => '{"waist":80,"height":170}',
  ],
]));
$task = json_decode($res, true);

body := bytes.NewBufferString(`{"waist":80,"height":170}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/health/waist-height-ratio", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)

Example request

{
  "waist": 80,
  "height": 170
}

Example response

{
  "task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
  "type": "health.waist_height_ratio",
  "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.

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