Expected Value (EV)
Also known as: EV, +EV, -EV
The average profit or loss per bet over the long run, given the odds and your estimated probability of winning.
Expected Value is the math behind whether a bet is good or bad. It calculates the average return per bet if you made the same wager infinite times.
Formula: EV = (Win Probability × Win Amount) − (Loss Probability × Loss Amount)
Example: Bet $100 at +120 on a coin flip you believe is truly 50/50.
- 50% × $120 = $60 expected win
- 50% × $100 = $50 expected loss
- EV = +$10 per bet
That’s a +EV bet. Any wager where your estimated win rate beats the implied probability is +EV. The whole craft of betting is identifying +EV opportunities.
Books survive because most public bets are -EV by a small margin (the vig). Sharps survive because their average bet is +EV.