Expected value (EV) is the average result of a bet over the long run. EV = (win chance × profit) − (lose chance × stake).
A +EV bet makes money over time; a −EV bet loses money over time. Any single bet can still go either way.
A bet is +EV when your win chance is higher than the implied probability of the odds. Finding those bets, often by comparing with fair odds, is the goal of sharp betting.
How it works
Expected value is the most important idea in betting, because it separates good bets from good results. A bet can win and still have been a poor bet, or lose and have been a great one.
EV depends on two things: the odds you get and the true chance of winning. The odds are easy to see. The true chance is the hard part, and it's where all the skill lies.
Most bettors estimate it in one of three ways:
- Their own model or analysis.
- fair odds from a sharp market, with the vig removed.
- Line movement, betting before the market moves toward their view.
A few common misunderstandings:
- +EV doesn't mean the bet wins. It means it would make money if repeated many times.
- Most standard bets are −EV. The sportsbook's margin makes sure of that.
- Small edges add up. A 2% to 5% EV on standard markets is very good.
Promotions like an odds boost are one of the easiest places to find +EV bets. The expected value calculator works out EV for any bet.
Examples
- Example 1
$100 at +120 that wins 50% of the time: (0.5 × $120) − (0.5 × $100) = +$10 EV.
- Example 2
A -110 bet that truly wins 55% of the time has an EV of about +$5.00 for every $100 staked.
- Example 3
A three-leg parlay of true 50/50 legs, each at -110, has an EV of about −13%. A $10 bet expects to lose $1.30.
- Example 4
A coin-flip bet normally priced at +100 is boosted to +120. EV is 0.5 × $120 − 0.5 × $100 = +$10 per $100 staked.
Common questions
How do you calculate expected value in betting?
Multiply your win chance by the profit if you win, then subtract your lose chance times your stake. If the result is positive, the bet is +EV.
What does +EV mean in sports betting?
A bet where the odds pay more than they should for the true chance of winning. Over many similar bets, +EV bets are expected to make a profit.