ForHosting KIT · Developer Utilities

Contribution margin calculator

Contribution margin is the money each sold unit leaves after its variable cost is paid, before any fixed cost is touched.

● BetaFree · in your browser

Run — free How it works & API

Use it from WebAPIEmailTelegramApp soon

Managers, cost accountants, and pricing teams use that remainder to decide whether a SKU should stay on the list, how deep a discount can go, and how many units a campaign must sell before overhead is covered. This contribution margin calculator takes selling price per unit and variable cost per unit, subtracts to obtain contribution margin per unit, then divides that remainder by selling price to obtain the contribution margin ratio and the matching percentage. Zero variable cost is allowed and yields a one hundred percent ratio. A selling price of zero is rejected because the ratio would divide by zero. A unit that does not cover its own variable cost returns a negative contribution margin instead of hiding the loss. The same pure function powers the free browser widget and the API, so a check on the landing page matches a later script. Successful calls are billed at $0.002; invalid input is not charged.

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/finance/contribution-margin

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/finance/contribution-margin \
  -H "Authorization: Bearer $KIT_KEY" \
  -H "Content-Type: application/json" \
  -d '{"selling_price":50,"variable_cost":30}'

const res = await fetch("https://api.kit.forhosting.com/finance/contribution-margin", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.KIT_KEY}`,
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "selling_price": 50,
    "variable_cost": 30
  })
});
const { task_id } = await res.json();

import os, requests

res = requests.post(
    "https://api.kit.forhosting.com/finance/contribution-margin",
    headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
    json={
    "selling_price": 50,
    "variable_cost": 30
},
)
task_id = res.json()["task_id"]

<?php
$res = file_get_contents("https://api.kit.forhosting.com/finance/contribution-margin", false, stream_context_create([
  "http" => [
    "method"  => "POST",
    "header"  => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
    "content" => '{"selling_price":50,"variable_cost":30}',
  ],
]));
$task = json_decode($res, true);

body := bytes.NewBufferString(`{"selling_price":50,"variable_cost":30}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/finance/contribution-margin", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)

Example request

{
  "selling_price": 50,
  "variable_cost": 30
}

Example response

{
  "task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
  "type": "finance.contribution_margin",
  "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 1000000000000

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 →