Expected value is the long-run average outcome of a bet if you placed it infinite times. Positive EV means the bet makes money over time; negative EV means it loses. Enter your stake, the offered odds, and your honest win probability. Last updated: May 2026.
Expected value (EV) is the average outcome per bet if you could replay the exact wager forever. A +$5 EV bet earns about $5 per attempt on average, even though each individual bet wins or loses fully.
EV = (win probability × profit if won) − (loss probability × stake). If your stake is $100 at +150 odds and you estimate a 45% win chance: EV = (0.45 × $150) − (0.55 × $100) = $67.50 − $55 = +$12.50.
The win rate you'd need to exactly break even at the given odds. It equals 1 ÷ decimal odds. If your true probability is higher than break-even, the bet is +EV. If lower, it's -EV.
It's worth betting in the long run if your probability estimate is accurate. In the short run, variance dominates — even a 60% +EV bet loses 40% of the time. Size your stakes using the Kelly Criterion to survive variance.
Compare your model's probability (or a sharp book's no-vig probability) against the offered odds. If your estimate is meaningfully higher than the implied probability, you've found a +EV bet.