Expected Value (EV)
The average profit or loss a bettor can expect per wager over the long run.
Expected value, usually shortened to EV, is a statistical measure of how a bet would shake out on average if you ran it many times under identical conditions. You compute it by multiplying each possible outcome by its probability, then adding those products together. Positive expected value (+EV) means a bet pays off over the long run, while negative expected value (-EV) means you’re set to lose money over time. Pros and serious recreational bettors alike treat EV as the single most important gauge of whether a wager is worth making.
Getting EV right means separating the result of one bet from the math driving it. A +EV bet can still lose on any given night, and a -EV bet can still win. What counts is the pattern that surfaces across hundreds or thousands of wagers. Bettors who keep finding and placing +EV bets will, given a big enough sample, turn a profit. Those who keep taking -EV bets watch their bankroll bleed out, hot streaks or not.
Example
Say you peg a team’s win chance at 55%, and the book hangs odds of +110 (decimal 2.10) on that team. The EV math on a $100 bet runs: (0.55 x $110) - (0.45 x $100) = $60.50 - $45.00 = +$15.50. So on average, you’d expect to clear $15.50 for every $100 staked on this type of bet over the long run. You’ll lose 45% of the time, but the payout on wins more than covers those hits.
Key Points
- Foundation of profitable betting: Every winning long-term strategy is built on spotting and exploiting positive expected value.
- Requires accurate probability estimates: An EV calculation is only as good as your read on the true probability of each outcome.
- Short-term results may differ: A single bet, or even a run of them, can land far from the expected value thanks to variance.
- The bookmaker’s edge is built-in: Most bets a book offers carry negative expected value for you, because the odds include a margin (vig) tilted toward the house.
- Comparison tool: EV lets you stack different wagers against each other on a shared scale, no matter the sport, bet type, or odds format.