Expected value is what a bet wins or loses on average if you could place it many times: EV = (chance of winning × profit) − (chance of losing × stake). A 100 bet at +150 with a true 45% chance has an EV of +12.50. At -110, a true coin flip has an EV of −4.55 per 100, which is the sportsbook's margin.
Key points
- Positive EV means your chance of winning is higher than the chance the odds imply.
- The odds already tell you the break-even: 52.4% at -110, 40% at +150.
- A good bet can lose and a bad bet can win. EV is about the price, not the result.
The formula
EV = p × profit if it wins − (1 − p) × stake
Take +150 for a 100 stake. If the team truly wins 45% of the time: 0.45 × 150 − 0.55 × 100 = 67.50 − 55 = +12.50. Over many such bets you'd expect to make 12.5% of what you stake. If the true chance were 40%, the EV would be exactly zero: that's what +150 implies.
EV at -110
| True win chance | EV per 100 staked |
|---|---|
| 50% | −4.55 |
| 52.4% | 0.00 |
| 55% | +5.00 |
| 60% | +14.55 |
Most bets at -110 are close to coin flips, which is why the house keeps about 4.5% of everything wagered at that price over time. See what the vig is.
Where positive EV comes from
To have positive EV, your estimate of the chance has to be better than the market's, and betting markets are sharp. In practice, edges usually come from:
- Better prices: the same bet at -105 instead of -110 lowers your break-even (see line shopping).
- Timing: betting before the market adjusts, which shows up as closing line value.
- Narrow knowledge: small leagues and markets the books price less carefully.
To compare your number with the market's, strip the margin out of the price with the implied probability calculator.
EV vs results
A +EV bet loses all the time, and a -EV bet wins all the time. Over a small number of bets the results are mostly noise; over thousands, they drift toward the EV. That's why practice records need size: see how many bets until you know.
Try it with free coins. FakeBet gives you real sportsbook odds, 500 free coins to start and a full record of every bet, so you can practice all of this without risking money. Get FakeBet on Google Play.