EV Calculator — Sports Betting Expected Value
Expected value is the foundation of sharp betting: the question isn't "will this win?" but "is the price right?" Enter your stake, the odds, and your own estimated win probability to see the bet's EV in dollars and as a percentage of your stake.
The formula
profit if win = stake × (decimal − 1) EV = p × profit − (1 − p) × stake EV % = EV / stake break-even p = 1 / decimal
Worked example
A $110 bet at -110 with a 55% chance of winning: profit if it wins is $100, so EV = 0.55 × $100 − 0.45 × $110 = +$5.50, or +5% of the stake. The break-even probability at -110 is 52.38%, so a 55% estimate is a 2.62-point edge.
How to use it well
- Get a fair probability by devigging a sharp line with the no-vig calculator.
- Size a +EV bet with the Kelly calculator rather than guessing.
- Remember EV is only as accurate as your probability. Small errors turn a "+EV" bet into a losing one.
This tool is informational, not betting advice. Verify all payouts with your sportsbook.
FAQ
What is expected value (EV) in sports betting?
Expected value is the average amount you'd win or lose per bet if you placed the same bet many times. A positive-EV (+EV) bet is one where your estimated chance of winning is higher than the odds imply.
How do I calculate EV?
EV = (probability of winning × profit if you win) − (probability of losing × your stake). For $100 at +120 with a 50% chance, that's 0.5 × $120 − 0.5 × $100 = +$10.
Where does the win probability come from?
From you — that's the hard part. Common sources are a model, or the devigged price from a sharp sportsbook. Use the no-vig calculator to turn a market's odds into fair probabilities, then plug that in here.
Does +EV mean I'll win this bet?
No. EV is a long-run average. A +EV bet still loses often; the edge only shows up across many bets, and only if your probability estimate is accurate.