Among Us impostor probability
In a 10-player lobby with 2 impostors, your chance of being impostor is exactly 1/5, or 20%, across 45 possible impostor teams. Enter the lobby size and the impostor seats to settle the odds before the round starts. Free in your browser.
- Free
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- Your data stays on your device
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Worked example
- Crew size
- 10
- Impostors
- 2
- Probability
- 0.2
- Percent
- 20
- Probability fraction
- 1/5
- Combinations
- 45
Among Us assigns impostor seats by drawing a fixed number of players uniformly from the live crew, so the chance that you personally are an impostor is exactly the impostor count divided by the crew size. Classic lobbies are ten players with two impostors (one fifth) or fifteen players with three impostors (also one fifth).
What Among Us impostor probability actually measures
Among Us does not flip a biased coin for every player independently. The lobby host sets how many impostor seats exist, then the match draws that many players uniformly without replacement from the live crew. A ten-player lobby with two impostors yields one fifth; a fifteen-player lobby with three impostors is also one fifth; eight players with one impostor is one eighth.
Zero impostors yields probability zero because everyone is a crewmate. When every remaining player is an impostor the probability is one. Nothing in the result depends on a clock, a random draw, or a remote service: the assignment model is fully determined by the two integers you send.
Use this page when you want a transparent number you can quote in a lobby, a stream overlay, or a homework write-up without arguing about house rules that the official random assignment does not actually use.
Where hosts, streams, classrooms, and tools use this number
Lobby hosts use the ratio before a round starts: ten players with two impostors feels different from ten with three, and quoting the exact personal chance (one fifth versus three tenths) stops arguments that are really about seat count, not luck. Streamers and Discord bots surface the same figure on an overlay so viewers see why a favorite player keeps landing crewmate in a packed fifteen-player lobby with only two seats.
Teachers treat Among Us as a familiar urn: drawing k impostors from n players is sampling without replacement, and P(a named student is drawn) equals k over n, which is a clean door into combinations, complements, and why C(n, k) counts the teams. Puzzle and game-tool authors call the contract from scripts to seed tables, to check Monte Carlo role-assignment code against the exact small cases, or to power a tutorial UI that must show both a fraction and a percent without inventing floating noise.
Homework drills need a fast offline oracle so students can check work without opaque calculator apps that silently round too early. Keep requests within the published ceilings, pin the rounded probability in tests, and you get reproducible impostor chances for overlays, LMS plugins, and edge workers without standing up a combinatorics library of your own.
What you can do with it
Balance a live Among Us lobby
Before starting a round, convert crew size and impostor seats into the exact chance each player is impostor so the table agrees on difficulty.
Stream overlay and Discord bots
Show P(you are impostor) and the number of possible impostor teams on an overlay or bot command from the same two integers the host already knows.
Classroom sampling without replacement
Use a familiar game to teach P(a named player is drawn) = k/n and C(n, k) as the size of the uniform team sample space.
FAQ
How is Among Us impostor probability calculated?
When k impostor seats are drawn uniformly from n players, the chance a given player is chosen is k/n, which equals C(n-1, k-1)/C(n, k). A ten-player lobby with two impostors is 2/10 = 1/5.
What does the combinations field mean?
Ten players and two impostors yield 45 possible pairs.
What are my odds of being impostor with 15 players and 3 impostors?
One fifth, the same as a lobby of ten players with two impostors. Your personal chance is always the number of impostor seats divided by the number of players in the lobby.
Does Among Us roll a separate chance for each player?
No. The host sets how many impostor seats exist, and the match draws exactly that many players from the crew without replacement. That is why the chance depends only on seats and lobby size, not on luck streaks.
What is my chance of being a crewmate?
Take the complement: players minus impostors, divided by players. With zero impostors everyone is a crewmate, and when every remaining player is an impostor, the impostor chance becomes one.
Related tools
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
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/game/among-us \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"crew_size":10,"impostors":2}'const res = await fetch("https://api.kit.forhosting.com/game/among-us", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"crew_size": 10,
"impostors": 2
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/game/among-us",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"crew_size": 10,
"impostors": 2
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/game/among-us", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"crew_size":10,"impostors":2}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"crew_size":10,"impostors":2}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/game/among-us", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"crew_size": 10,
"impostors": 2
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "game.among_us",
"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
Published price — no tokens, no invented credits. A failed task is never charged.
Limits
max_crew_size | 1000 |
max_impostors | 1000 |
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. |
Technical notes
This calculator accepts those two integers, rejects negatives and any request where impostors exceed crew size, and returns the probability as a decimal, a percent, and a reduced fraction, plus the number of distinct impostor teams C(crew_size, impostors). The same deterministic module powers the free browser tool and the API: no randomness, no clock, and no network. Successful API calls cost $0.002; invalid input is not billed.
What Among Us impostor probability actually measures
For any specific player, including you, the probability of occupying one of those seats is therefore the ratio of impostor seats to crew size: impostors divided by crew_size. That identity is the same combinatorics identity C(crew_size minus one, impostors minus one) over C(crew_size, impostors), which counts the impostor teams that include you against every possible impostor team of the required size. The calculator also returns C(crew_size, impostors), the number of distinct impostor line-ups the match could have assigned, because that integer is the size of the uniform sample space over teams. If you need the chance of surviving the assignment as a crewmate instead, take the complement one minus that ratio, which is crew_size minus impostors over crew_size.
Input contract, errors, and the shape of a successful result
POST two required integers: crew_size, the number of players in the lobby, and impostors, the number of impostor seats the host configured. Aliases crew, players, and n are accepted for crew_size; k and impostor_count are accepted for impostors, so spreadsheets and query strings can reuse the same contract. crew_size must be a positive integer from one through one thousand. impostors must be a non-negative integer no larger than crew_size and no larger than one thousand. Either value negative is invalid_input; impostors that exceed crew size is invalid_input with a message that names both fields; missing fields, empty strings, fractions, and non-numeric tokens fail the same way and are not billed. On success the body echoes the validated crew_size and impostors, then probability as a decimal rounded to twelve places, percent as one hundred times that ratio, probability_fraction as the fully reduced impostors over crew_size string, combinations as the exact binomial coefficient C(crew_size, impostors) written as a decimal string so large values never lose digits, and a formula field restating P equals impostors over crew_size. Example: crew_size ten and impostors two yields probability 0.2, percent 20, fraction 1/5, and forty-five possible impostor pairs. Pair the free browser run on this page with the priced API when you need the identical mathematical result inside a bot, overlay, or test suite without re-implementing the ratio and the binomial coefficient yourself. Failed validation does not consume balance; a successful call is billed at $0.002.
Where hosts, streams, classrooms, and tools use this number
On this page the work runs entirely in your browser; through the API each successful lookup costs $0.002, invalid input is not charged, and nothing is stored after the response returns. That split—free interactive exploration and a priced, identical API—lets you move from a lobby screenshot to an automated pipeline without changing the mathematical result.
Technical questions
What happens if impostors exceed crew size?
The task fails with invalid_input. You cannot assign more impostor seats than there are players; the message names both crew_size and impostors.
Are negative crew sizes or impostor counts allowed?
No. Either value negative is invalid_input and is not billed. crew_size must be at least 1; impostors must be a non-negative integer no larger than crew_size.
What does the Among Us impostor probability calculator cost?
The browser tool is free. API requests use prepaid balance at $0.002 per successful call; invalid input is not billed.