ForHosting KIT · Developer Utilities

Intermittent fasting window calculator

Intermittent fasting window 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

How is the eating window calculated?

eating_start is first_meal. eating_end is first_meal plus the eating hours from the F:E ratio, modulo 24 hours. fasting_start equals eating_end; fasting_end equals fasting_start plus the fasting hours, landing back on first_meal.

Which input fields are required?

first_meal (HH:MM, 24-hour) and fasting_ratio (F:E with positive integers summing to 24). Aliases meal_time, eating_start, first_meal_time, ratio, protocol, and if_ratio are accepted. Invalid input returns invalid_input and is not billed.

Why must fasting plus eating equal 24 hours?

This tool models a single daily intermittent-fasting cycle. F+E=24 keeps the schedule unambiguous and fully deterministic for goldens and SEO demos. Multi-day protocols are out of scope.

Is this medical advice about whether I should fast?

No. It only computes clock boundaries for a chosen ratio. It does not assess safety, calories, or clinical suitability. Seek professional guidance when medical decisions depend on fasting.

What does the intermittent fasting window calculator cost?

The browser widget is free. API calls use prepaid KIT balance at $0.002 per successful task; 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/if-eating-window

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/if-eating-window \
  -H "Authorization: Bearer $KIT_KEY" \
  -H "Content-Type: application/json" \
  -d '{"first_meal":"12:00","fasting_ratio":"16:8"}'

const res = await fetch("https://api.kit.forhosting.com/health/if-eating-window", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.KIT_KEY}`,
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "first_meal": "12:00",
    "fasting_ratio": "16:8"
  })
});
const { task_id } = await res.json();

import os, requests

res = requests.post(
    "https://api.kit.forhosting.com/health/if-eating-window",
    headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
    json={
    "first_meal": "12:00",
    "fasting_ratio": "16:8"
},
)
task_id = res.json()["task_id"]

<?php
$res = file_get_contents("https://api.kit.forhosting.com/health/if-eating-window", false, stream_context_create([
  "http" => [
    "method"  => "POST",
    "header"  => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
    "content" => '{"first_meal":"12:00","fasting_ratio":"16:8"}',
  ],
]));
$task = json_decode($res, true);

body := bytes.NewBufferString(`{"first_meal":"12:00","fasting_ratio":"16:8"}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/health/if-eating-window", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)

Example request

{
  "first_meal": "12:00",
  "fasting_ratio": "16:8"
}

Example response

{
  "task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
  "type": "health.if_eating_window",
  "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 →