What Is Expected Value in Sports Betting?

Expected value — EV — is the average amount a bet would win or lose per dollar staked if you could place the same bet many times. It compares the price you are offered to the estimated fair probability of the outcome.

The short answer

Every bet has a price and a chance of winning. If the price pays more than the chance justifies, the bet has positive expected value (+EV). If it pays less, the bet is -EV. Because sportsbooks build a margin into their prices, most bets offered are slightly -EV by default.

A worked example

ExampleSuppose a fair coin flip pays +100 (you double your money). Your EV is exactly 0% — over many flips you break even. Now suppose a book offered +105 on heads. Each $100 bet now has an estimated EV of +2.5%: half the time you lose $100, half the time you win $105, for an average profit of $2.50 per flip. That small gap, repeated, is the entire game.

What EV does not tell you

EV is a long-run average, not a prediction. A +EV bet can lose — most individual bets are close to coin flips. And EV is only as good as the probability estimate behind it. EVScout computes estimated EV by de-vigging market prices; it does not claim to know the true probability of any game.

Key terms

Implied probability — the win chance baked into a price, including the sportsbook's margin. Estimated fair probability — that chance after removing the margin. Estimated EV — the gap between the offered price and the estimated fair price, expressed as a percentage of stake.

Try the math yourself

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