Implied Probability Calculator

About this calculator

Bookmakers express the price of a bet as decimal odds — a number like 2.50 that tells you your total return (stake included) for every 1 unit staked. Converting those odds into a probability is simple: implied probability = 1 / decimal odds, so 2.50 implies a 40% chance the bookmaker is pricing in. Because bookmakers build in a profit margin (the "overround" or "vig"), the implied probabilities across all outcomes of an event typically add up to more than 100% — the excess is the house edge.

Bettors use implied probability to judge whether odds represent good value: if your own estimate of an outcome's true probability is higher than the bookmaker's implied probability, the bet may be worth taking. It's also how bettors compare odds across bookmakers, spot arbitrage opportunities, and translate between American, fractional and decimal odds formats used in different markets (US sportsbooks vs. UK/European exchanges).

This calculator converts any decimal odds you enter into the implied win probability the bookmaker is quoting.