Expected value calculator
Expected value = win probability × profit − loss probability × stake. A $100 bet at +110 that wins 50% of the time has an EV of +$5.00; the same bet at −110 has −$4.55. Enter your odds and probability, or a sharp line, to see the EV.
Checked 2026-11-07. Source: formula and table below.
19+ in most of Canada (18+ in Alberta, Manitoba and Quebec), 21+ in most US states. A calculator shows what a bet pays, not how likely it is to win. Free help: 1-800-GAMBLER (US), ConnexOntario 1-866-531-2600 (Ontario), 211 (Alberta). More help.
How expected value is calculated
EV = P(win) × (decimal odds − 1) × stake − P(lose) × stake
break-even win rate = 1 ÷ decimal odds · fair odds = 1 ÷ P(win)
Worked example with a sharp line: a sharp book prices a game at −105 / −115. Removing its 4.71% margin gives the first side a fair chance of 48.92% (fair odds +104). If another book offers +110 on that side, $100 has an EV of 48.92% × $110 − 51.08% × $100 = +$2.72.
To size a +EV bet, see the Kelly criterion calculator; to take the margin out of any market, the no-vig calculator.
EV of a $100 bet by odds and win probability
| Odds | Break-even | EV at 40% | EV at 50% | EV at 60% |
|---|---|---|---|---|
| -200 | 66.67% | −$40.00 | −$25.00 | −$10.00 |
| -150 | 60.00% | −$33.33 | −$16.67 | −$0.00 |
| -110 | 52.38% | −$23.64 | −$4.55 | +$14.55 |
| +100 | 50.00% | −$20.00 | +$0.00 | +$20.00 |
| +110 | 47.62% | −$16.00 | +$5.00 | +$26.00 |
| +150 | 40.00% | +$0.00 | +$25.00 | +$50.00 |
| +200 | 33.33% | +$20.00 | +$50.00 | +$80.00 |
| +300 | 25.00% | +$60.00 | +$100.00 | +$140.00 |
Questions
What is expected value in betting?
The average profit or loss per bet if you placed the same bet many times: win probability × profit − loss probability × stake. $100 at +110 on a 50% chance has an EV of +$5.00.
What is a +EV bet?
A bet whose odds pay more than its true chance of winning deserves, so its expected value is positive. At −110 you need to win more than 52.38% of the time just to break even.
How do I find the true probability?
Either your own estimate, or the price at a sharp bookmaker with the margin removed. A −105/−115 line implies 48.92% for the first side once the 4.71% margin is taken out.
Does positive EV mean I will win?
No. EV is an average over many bets. A single +EV bet loses often, and results swing widely over short runs; the estimate of probability can also be wrong.