Round-robin matches calculator — games and rounds for n teams

Run — free

Runs in your browser. Free, unlimited — your data never leaves this page.

Organizers still need two numbers before they book courts, referees, or broadcast slots — how many games will be played in total, and how many rounds the schedule will take if each team plays at most once per round. The total is always the binomial coefficient n choose two, written n times n minus one over two. The number of rounds depends on parity: when n is even the field pairs completely every round and finishes in n minus one rounds; when n is odd one team sits out each round and the tournament needs n rounds so every side still meets n minus one opponents. This capability accepts an integer team count n of at least two and returns games, matches, rounds, games per round, and short formula strings computed with pure integer arithmetic. Values below two are rejected with a clear validation error. The free browser tool and the paid API share one pure function, so league planners and automated pipelines never disagree on the same n.

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/combo/round-robin

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/combo/round-robin \
  -H "Authorization: Bearer $KIT_KEY" \
  -H "Content-Type: application/json" \
  -d '{"n":8}'

const res = await fetch("https://api.kit.forhosting.com/combo/round-robin", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.KIT_KEY}`,
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "n": 8
  })
});
const { task_id } = await res.json();

import os, requests

res = requests.post(
    "https://api.kit.forhosting.com/combo/round-robin",
    headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
    json={
    "n": 8
},
)
task_id = res.json()["task_id"]

<?php
$res = file_get_contents("https://api.kit.forhosting.com/combo/round-robin", false, stream_context_create([
  "http" => [
    "method"  => "POST",
    "header"  => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
    "content" => '{"n":8}',
  ],
]));
$task = json_decode($res, true);

body := bytes.NewBufferString(`{"n":8}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/combo/round-robin", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)

Example request

{
  "n": 8
}

Example response

{
  "task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
  "type": "combo.round_robin",
  "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

`min_n`	2
`max_n`	100000

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 →