What is Expected Value (EV) in Betting?
Learn how expected value measures the long-term profitability of a betting decision and how to calculate it from odds and estimated probability.
Expected value in one sentence
Expected value estimates the average profit or loss from repeatedly making the same type of bet. Positive EV does not promise that one bet will win; it describes the quality of the price over many bets.
The basic formula
For decimal odds, EV per unit can be written as: probability of winning × net profit when winning − probability of losing × stake.
At odds 2.00 with a 55% estimated chance, EV is 0.55 × 1.00 − 0.45 × 1.00 = +0.10 units, or +10% of stake.
Probability is the difficult part
The calculation is simple; producing a well-calibrated probability is not. Use team news, form, tactical fit, scheduling and market information, and update your estimate when the facts change.
EV and value bets
A value bet exists when your estimated probability is higher than the break-even probability implied by the available odds. EV expresses the size of that estimated edge.
Track results over a large sample
Short runs are dominated by variance. Record the price taken, closing price, stake and result so you can judge whether your process is finding sustainable value.
Continue learning
New to football predictions? Read our starting guide: How to Read a Football Prediction.