Expected value (EV) calculator for sports betting
Expected value is what a bet is worth on average if you could make it many times. A positive EV bet is one where the odds pay more than the true chance of winning justifies. It still loses often; the edge shows up over volume.
Enter the odds you can bet and the fair odds for the same side, usually devigged from a sharp book. The calculator shows the expected value for your stake in dollars and as a percentage.
Free, no account needed. Everything is worked out in your browser and nothing you type is saved.
How to use the expected value calculator
- 1Enter the Bet Odds: the price you can actually bet at your sportsbook.
- 2Enter the Fair Odds for the same side. If you do not have them, devig a sharp book’s market with the no-vig calculator first.
- 3Enter your stake.
- 4Read Expected Value and EV %. Positive means the price beats fair value, and the Kelly calculator can then size the bet.
Worked example: +120 against fair +104
A sportsbook offers +120 on a side that devigs to +104 at a sharp book. You bet $100.
- Fair win probability (+104)
- 49.02%
- Profit if it wins
- $120.00
- Loss if it loses
- $100.00
- Expected value
- $7.84
- EV %
- 7.84%
EV = 49.02% × $120 − 50.98% × $100 = $7.84. On average each $100 bet at this price gains $7.84, even though it loses slightly more than half the time.
Frequently asked questions
What is positive EV betting?
Betting only when the odds offered are better than the fair odds for that outcome. You are not predicting winners; you are buying prices that pay more than they should. Over enough bets, results trend toward the expected value.
Where do fair odds come from?
Most +EV bettors devig a sharp sportsbook or an exchange, whose prices are the best available estimate of the true probability. The no-vig calculator does that from both sides of a market.
How much EV is worth betting?
Fair odds are an estimate, so very small edges can be noise. Many bettors set a minimum of a few percent, and ask for more on markets where the sharp line is less reliable, such as player props and smaller leagues.
What is the break-even win rate for a bet?
The implied probability of the odds. At -110 you need to win 52.38% of the time to break even; at +120, 45.45%. Any true probability above that is positive EV.
Free now, free for good
Every BreadSync calculator is free to use without an account, and that is not changing. They work on the odds you type in.
BreadSync Pro’s +EV finder does this for every line at 130+ sportsbooks, comparing each price with the sharp no-vig line and sizing it with Kelly.
Related calculators
- No-Vig CalculatorStrip the vig from a two-way market to get fair odds and win probability, four devig methods.
- Kelly Criterion CalculatorSize a bet from your edge and bankroll, with full, half and quarter Kelly.
- Odds ConverterConvert between American, decimal and fractional odds and implied probability.
- Arbitrage CalculatorCheck whether two or three prices are an arb and split your stake so every outcome pays the same.
21+. Worked examples are illustrative and use made-up prices; real odds change constantly. Calculator results are estimates for information only, not betting advice or a guarantee of profit. BreadSync is not a sportsbook and does not accept wagers. If gambling stops being fun, call 1-800-GAMBLER.