Expected Value (EV) Calculator
Enter the odds, your honest win probability and a stake to see the bet's expected value — the only number that separates investing from donating.
Expected value of this bet
+4.0%
If your probability estimate is right, this bet earns 4.00 per 100 staked, on average, over many repeats.
Break-even win rate at odds 2.00
50.00%
win more often than this and the bet is +EV
Your edge over break-even
+2.00 pts
your estimate minus the market's implied probability
The hard part is not this formula — it is whether your probability estimate is honest. EV computed from a wishful probability is fiction.
The formula is easy. The probability is not.
Every profitable bettor in history got there the same way: repeatedly taking prices that paid more than the true probability was worth. The formula on this page is all the math that requires. The catch is the input — your probability estimate has to be better calibrated than the market's, and the market is the aggregate of everyone with money on the line.
That is why serious bettors validate their estimates against reality: if your bets consistently beat the closing line, your probabilities are genuinely sharper than the market's. If not, the EV you compute is imagination. Our free CLV calculator checks a single bet; the EV guide walks the full logic with real numbers.
SmartBet Lab measures your real edge from your synced betting history — actual CLV on every matched bet, not estimates. No more guessing whether your probabilities are honest.
Frequently asked questions
What is expected value (EV) in betting?
EV is the average profit or loss of a bet if you could repeat it many times: EV = probability × (odds − 1) − (1 − probability). A +EV bet earns money in the long run; a −EV bet loses money no matter how it feels short-term.
Where does the win probability come from?
That is the entire game. The market’s implied probability is 1 ÷ odds (minus the margin); your edge exists only if your estimate is more accurate than the market’s. Most bettors overestimate their probabilities — which is why most bets that feel like value are not.
Is a +EV bet guaranteed to win?
No. EV describes the long-run average, not one outcome. A +4% EV bet still loses close to half the time at even odds — the profit only shows up over hundreds of bets, which is why sample size and variance matter as much as the edge itself.