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Best-of-Seven Series Probability Calculator

From a single-game win probability, compute the chance a team wins a best-of-seven series (first to 4 wins), the odds of each outcome (4-0 to 4-3), and the expected number of games.

Input

Enter the per-game win probability to compute the chance the team wins the series by reaching the required wins first, along with the odds of each finish.

%

Enter 0 to 100 (e.g. 55 means a 55 percent chance to win one game)

wins

Wins required to clinch the series (4 for best-of-seven)

Result

Series win probability

60.8%

Average games

5.8 games

Sweep (fewest games) probability

9.2 %

Chance it goes to game 7

30.3 %

4-09.24-116.54-218.54-316.7

Probability of each finish

FinishGamesProbability
4-04 games9.2 %
4-15 games16.5 %
4-26 games18.5 %
4-37 games16.7 %

The probability of winning in exactly wins-needed wins and k losses is C(wins-needed minus 1 plus k, k) times p to the wins-needed power times (1-p) to the k power; their sum is the series win probability.

How it works

  • Assumes the per-game win probability p is constant and each game is independent. Home advantage and pitching matchups are not modeled.
  • The probability of winning in exactly 4 wins and k losses is C(3+k, k) times p to the 4 times (1-p) to the k, where k is the loss count from 0 to 3.
  • The series win probability is the sum of the probabilities of each finish (4-0, 4-1, 4-2, 4-3).
  • The expected number of games weights both the finishes your team wins and the finishes it loses by their probabilities.
  • Wins needed defaults to 4 (best-of-seven), but you can change it to any value such as first to 3 or first to 5.

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