EV calculator
Enter the odds you can get and the bet's true chance of winning, from a sharp market or your own estimate, to see whether it's worth taking.
- True chance
- 50.0%
- Fair odds
- +100
- Break-even at your odds
- 45.5%
- Kelly stake
- 8.3% of bankroll (¼ Kelly 2.1%)
How it works
EV = chance of winning × profit if it wins − chance of losing × stake. Positive means the price is better than the bet's true odds; negative means the book has the edge.
With a sharp market, the true chance is your side's share once the margin is removed: at −110 / −110 that's 50%, so any price above +100 on that side is +EV.
Questions
What is expected value (EV) in betting?
What a bet returns on average if you made it many times: the chance it wins times what it pays, minus the chance it loses times your stake. A bet at +120 that truly wins 50% of the time returns +10% on average; one that wins 45% returns −1%.
Where does the true win chance come from?
Most bettors use a sharp market: take both sides of the same bet at a sharp book and remove its margin, which gives a fair price to compare against. You can also type your own estimate if you have a model.
What is the Kelly stake?
The share of your bankroll that grows it fastest for a given edge and price. Full Kelly swings hard, so most bettors use a quarter of it or less. When the edge is negative, Kelly says not to bet.
Does positive EV mean the bet will win?
No. A +EV bet still loses often; the edge only shows up over many bets. That's why line shopping matters: taking the best price on every bet is the most reliable way to keep EV positive.
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