Odds to Probability Calculator
Convert between odds and probability in both directions.
Probability
75.00%
Odds simplified
3 : 1
Decimal (betting) odds
1.333
Odds ≠ probability
3:1 odds in favor means 3 successes per 1 failure — a probability of 3/(3+1) = 75%, not 3%. The conversion is odds = p/(1−p) and back p = odds/(1+odds). Confusing the two systematically misprices anything from bets to medical risks.
Bookmaker arithmetic
Betting sites quote decimal odds (payout per unit staked) whose implied probability is 1/odds. Sum a market's implied probabilities and you'll get over 100% — the excess (the 'vig') is the bookmaker's margin, and it's why converting odds honestly matters.
Frequently asked questions
- How does the Odds to Probability Calculator work?
- Convert between odds and probability in both directions.
- Is the Odds to Probability Calculator free to use?
- Yes. The Odds to Probability Calculator is completely free, runs entirely in your browser, and requires no account or sign-up. Your inputs never leave your device.
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