Expected value (EV) calculator for sports bets
Short answer: EV per $100 staked = chance of winning x profit - chance of losing x $100. At -110 (profit $90.91) with a 55% chance: 0.55 x 90.91 - 0.45 x 100 = +$5.00. The break-even chance at -110 is 52.38%. Enter a price and your probability, or a sharp book's two prices to use its no-vig probability.
| Price | -110 (decimal 1.909) |
| Win probability used | 55.00% (your estimate) |
| Break-even probability at this price | 52.38% |
| Expected value per $100 | +5.00 (+5.00%) |
| Fair price for that probability | -122 |
| Edge over break-even | +2.62 points |
Showing a worked example. Enter your own numbers above; the result's link can be shared.
The formula
EV = P(win) × profit if it wins − P(lose) × stake. At American odds of -110, a $100 stake profits $90.91; at +150 it profits $150. With a 55% chance at -110: 0.55 × 90.91 − 0.45 × 100 = +$5.00 per $100, or +5%.
The break-even probability is the price's implied probability: at -110 you need to win 52.38% of the time just to break even. Any bet is +EV only if its real chance is above that number.
Where the probability comes from
Nobody knows the real chance. The usual stand-in is a sharp book's no-vig probability: enter Pinnacle's two prices for the same line and the calculator removes the vig first (the same arithmetic as the no-vig calculator). That estimate is only as good as the sharp book is on that market; see is Pinnacle sharper than DraftKings.
Why small EV numbers matter
A +2% edge means $2 per $100 on average, with a standard deviation near $100 per bet at even odds. It takes hundreds of bets for a real edge to show through the noise, which is why OpenSlate publishes every pick it has published, losses included, rather than highlights.
Other tools: No-vig calculator: remove the vig from any two-way odds · Odds converter: American, decimal, fractional and implied probability. Guides: Learn.
Arithmetic only, not betting advice. 21+. Problem gambling? Call 1-800-GAMBLER.