Guide
Expected value in betting
Expected value is the average profit or loss of a bet if the same decision could be repeated across a large number of comparable opportunities. It is the number that separates a good bet from a bet that happened to win.
Published 2026-08-25 · Last reviewed 2026-09-01 · BetBuddy editorial
The formula
Expected value weighs the profit if the bet wins against the stake lost if it does not, using your own probability estimate rather than the market's.
EV = p × (odds − 1) × stake − (1 − p) × stake
Worked example: 2.00 at an estimated 55%
Odds of 2.00 return €1.00 profit per €1 staked. With an estimated probability of 55%, the loss side carries the remaining 45%.
EV per €1 = (0.55 × €1.00) − (0.45 × €1.00) = €0.55 − €0.45 = +€0.10. The expected return is +10% of stake.
The break-even probability at 2.00 is 50%. The estimate of 55% is what creates the +10%; drop the estimate to 48% and the same price returns −€0.04 per €1, a −4% expectation.
(0.55 × €1.00) − (0.45 × €1.00) = +€0.10 per €1 staked
EV at other prices
The same arithmetic at different prices shows how quickly the required accuracy of the estimate rises as prices shorten.
| Odds | Break-even p | Estimated p | EV per €1 |
|---|---|---|---|
| 1.80 | 55.6% | 60% | +€0.08 |
| 2.00 | 50.0% | 55% | +€0.10 |
| 2.50 | 40.0% | 44% | +€0.10 |
| 3.50 | 28.6% | 30% | +€0.05 |
| 2.00 | 50.0% | 48% | −€0.04 |
Positive EV is not a guaranteed win
Expected value is an expectation across repeated comparable opportunities, not a property of the next bet. A +10% EV bet at 2.00 still loses 45 times in 100 under its own assumptions.
It is also only as good as the probability that went into it. BetBuddy does not know a match's true probability with certainty, and neither does any bookmaker; both are working with estimates. Treat every EV figure as conditional on an estimate that may be wrong.
Turning EV into a total
Over a run of bets, expected profit is the sum of each bet's EV. Twenty bets averaging +€0.10 per €1 at a €10 stake have an expected profit of €20 — with a realistic range around that number wide enough to include a loss.
Comparing realised profit against summed EV is a useful diagnostic: a persistent, large gap in either direction usually means the probability estimates are miscalibrated rather than unlucky.