Free calculator
Calculate the expected value of a bet.
EV is the number that separates a value bet from a coin flip: your probability estimate, priced against the odds, expressed as a percentage and in euros per €100 staked.
EV is a long-run expectation, not a per-bet promise — a single positive-EV bet can still lose.
How to read the result
Expected value equals your probability estimate times the decimal odds, minus one, expressed as a percentage: EV% = (p × odds − 1) × 100.
EV is a long-run expectation. A bet at decimal 2.10 with a 52% probability estimate is worth +9.2% — about €9.20 of expected value per €100 staked. Any single bet at positive EV can still lose; the edge only shows up over many bets.
Your estimate is the whole game. The calculator checks consistency between the price and the probability you supply. It cannot tell you whether the estimate itself is any good — that is the research that separates a value bet from a guess.
The implied probability shown alongside is what the price itself implies. If your estimate is above it, the bet has positive EV on your numbers; below it, you are paying the margin twice.
Also see
De-vig / fair odds
Strip the bookmaker margin out of two- or three-way decimal prices and read the de-vigged fair odds and overround.
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Kelly stake
Size a single bet against your bankroll with full or fractional Kelly, and see why the fraction exists.
Open calculator →
Arbitrage stake split
Split a stake across outcomes for an equal return, and check whether the prices are an arbitrage at all before costs.
Open calculator →