ForHosting KIT · Developer Utilities

Probability of two recessive traits

When two parents are each heterozygous at the same two unlinked loci, classic Mendelian genetics asks how often an offspring will express both recessive phenotypes at once.

● BetaFree · in your browser

Run — free How it works & API

Use it from WebAPIEmailTelegramApp soon

Students meet this as the double-recessive corner of a sixteen-cell Punnett square; tutors and exam writers need the same fraction without redrawing the grid every time. This calculator accepts two dihybrid heterozygous genotypes such as AaBb and AaBb, checks that each locus is truly heterozygous and that both parents share the same two letters, then applies the product rule under independent assortment: one-fourth chance of the recessive phenotype at each locus multiplies to one-sixteenth for both together. The response returns the exact probability, the fraction 1/16, a percent form, the normalized cross string, and a short formula you can show beside homework or LMS feedback. Failed validation is not billed, so malformed genotypes cost nothing while correct textbook crosses stay deterministic across the free widget and the paid API path.

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/bio/punnett-probability-two-recessive

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/bio/punnett-probability-two-recessive \
  -H "Authorization: Bearer $KIT_KEY" \
  -H "Content-Type: application/json" \
  -d '{"parent1":"AaBb","parent2":"AaBb"}'

const res = await fetch("https://api.kit.forhosting.com/bio/punnett-probability-two-recessive", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.KIT_KEY}`,
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "parent1": "AaBb",
    "parent2": "AaBb"
  })
});
const { task_id } = await res.json();

import os, requests

res = requests.post(
    "https://api.kit.forhosting.com/bio/punnett-probability-two-recessive",
    headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
    json={
    "parent1": "AaBb",
    "parent2": "AaBb"
},
)
task_id = res.json()["task_id"]

<?php
$res = file_get_contents("https://api.kit.forhosting.com/bio/punnett-probability-two-recessive", false, stream_context_create([
  "http" => [
    "method"  => "POST",
    "header"  => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
    "content" => '{"parent1":"AaBb","parent2":"AaBb"}',
  ],
]));
$task = json_decode($res, true);

body := bytes.NewBufferString(`{"parent1":"AaBb","parent2":"AaBb"}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/bio/punnett-probability-two-recessive", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)

Example request

{
  "parent1": "AaBb",
  "parent2": "AaBb"
}

Example response

{
  "task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
  "type": "bio.punnett_probability_two_recessive",
  "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 →