Impostor Odds Calculator – Among Us

Enter the lobby size, impostor count, and how many players are still unconfirmed to see the exact probability that a given player is an impostor, plus the odds as a "1 in X" ratio and the number of possible impostor line-ups.

Quick Facts

Starting odds
P(impostor) = Impostors (K) ÷ Total players (N)
Impostors are assigned uniformly at random, so every player starts with the same K/N chance.
Updated odds
P(impostor now) = Hidden impostors ÷ Players remaining
Clearing an innocent player concentrates the same total odds onto fewer suspects.

Your Results

Calculated
Starting impostor odds
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Chance any one player was impostor at round start (K/N)
Current impostor odds
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Chance a random remaining player is impostor now
Odds ratio
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Same chance, written as "1 in X"
Possible impostor line-ups
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Ways the hidden impostors could be placed among remaining players

Ready

Set the lobby size, impostor count, and remaining players, then press Calculate.

About the Impostor Odds Calculator – Among Us

This tool works out the real probability that a given player is an impostor in Among Us, based on how impostors are actually assigned in the game: uniformly at random from the lobby. Enter the total number of players, the impostor count your host set, and how many players are still unconfirmed (not yet ejected, killed, or otherwise cleared), and the calculator returns the exact odds using basic probability and combinatorics — no guesswork or vague "suspicion meters."

The formula

With N total players and K impostors chosen uniformly at random at the start of a round, the probability that any one specific player is an impostor is:

  • Starting odds: P = K / N — for example, 2 impostors among 10 players gives every player a 20% chance.
  • Current odds: once E impostors have been caught and only R players remain unconfirmed, the same total probability mass is spread over fewer suspects: P = (K − E) / R. This follows from symmetry — since cleared players are known not to be impostors, the remaining impostors are equally likely to be any of the R players left.
  • Possible line-ups: the number of distinct ways the (K − E) hidden impostors could be distributed among the R remaining players is the binomial coefficient C(R, K − E) = R! / [(K − E)! × (R − K + E)!].

How to read the results

The starting odds show the baseline chance any player had before any information came in. The current odds update that figure using how many suspects remain and how many impostors are still uncaught — this is the number that matters mid-round. The odds ratio restates the same probability as "1 in X" for a more intuitive read, and the possible line-ups count shows how many distinct impostor arrangements are still consistent with what you know.

Assumptions

The model assumes impostors are assigned uniformly at random (true for the base game) and that any players you mark as "caught" or "cleared" were correctly identified — it does not account for meeting behavior, voting patterns, or task-completion tells, which real players use as additional evidence.

Frequently Asked Questions

How is the chance of being the impostor calculated?
At the start of a round, impostors are chosen uniformly at random from the lobby, so the probability any one specific player is an impostor equals the number of impostors (K) divided by the total number of players (N): P = K / N. With 2 impostors in a 10-player lobby, that is 2/10, or 20% per player.
Why do the odds change as the round goes on?
Once a player is confirmed crewmate (cleared by a task witness, an alibi, or an ejection that was not an impostor), the remaining hidden impostors must be among the players left. By symmetry the updated odds for any one remaining player are (K minus impostors already caught) divided by the number of players still remaining: (K-E) / R. Removing confirmed-innocent players from the pool concentrates the odds on whoever is left.
What does "1 in X" odds mean?
It is the same probability written as a ratio instead of a percentage: dividing the remaining players by the remaining impostors gives X, meaning roughly 1 out of every X remaining players is expected to be an impostor. A 25% chance is the same as 1 in 4.
How many impostors can an Among Us lobby have?
The host sets 1, 2, or 3 impostors for lobbies of 4 to 15 players in the standard game. This calculator assumes that fixed impostor count and a uniformly random initial assignment, which is how the base game selects impostors.

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