ForHosting KIT · Developer Utilities

Number of half-lives calculator

Counting half-lives is the intermediate step students and lab planners write before they convert a start amount into a remaining inventory.

● BetaFree · in your browser

Run — free How it works & API

Use it from WebAPIEmailTelegramApp soon

The definition is simple and unit-agnostic: the number of half-lives elapsed equals total elapsed time divided by the half-life of the species, so twenty hours with a ten-hour half-life is exactly two half-lives, and three days with a twelve-hour half-life is six half-lives when both times share the same unit. This capability accepts non-negative elapsed time and a strictly positive half-life, returns the full half-lives count together with the whole-number floor, the fractional remainder, and the pure exponential fraction remaining under one-half to the power of that count, and rejects a zero half-life with a clear invalid input error so pipelines never divide by zero by accident. Homework checkers, nuclear-medicine prep sheets, environmental inventory scripts, and tutoring apps can pin the same deterministic JSON in continuous-integration fixtures without embedding a chemistry CAS. The browser widget runs free on your device; the prepaid API charges $0.002 per successful item when servers and SDKs need the same contract.

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/chem/half-lives-elapsed

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/chem/half-lives-elapsed \
  -H "Authorization: Bearer $KIT_KEY" \
  -H "Content-Type: application/json" \
  -d '{"elapsed_time":20,"half_life":10}'

const res = await fetch("https://api.kit.forhosting.com/chem/half-lives-elapsed", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.KIT_KEY}`,
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "elapsed_time": 20,
    "half_life": 10
  })
});
const { task_id } = await res.json();

import os, requests

res = requests.post(
    "https://api.kit.forhosting.com/chem/half-lives-elapsed",
    headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
    json={
    "elapsed_time": 20,
    "half_life": 10
},
)
task_id = res.json()["task_id"]

<?php
$res = file_get_contents("https://api.kit.forhosting.com/chem/half-lives-elapsed", false, stream_context_create([
  "http" => [
    "method"  => "POST",
    "header"  => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
    "content" => '{"elapsed_time":20,"half_life":10}',
  ],
]));
$task = json_decode($res, true);

body := bytes.NewBufferString(`{"elapsed_time":20,"half_life":10}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/chem/half-lives-elapsed", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)

Example request

{
  "elapsed_time": 20,
  "half_life": 10
}

Example response

{
  "task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
  "type": "chem.half_lives_elapsed",
  "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