What Is Expected Value (EV) in Betting?

Expected value, usually shortened to EV, is the most useful idea in betting and the least understood. It answers one question: if you could place this exact bet over and over, how much would you win or lose on average per unit staked?

The formula

EV per unit = (probability of winning × profit on a win) − (probability of losing × stake).

With decimal odds, the profit on a win is the odds minus 1. At odds of 2.10 and a 52% chance of winning, the EV per unit is 0.52 × 1.10 − 0.48 × 1 = +0.092. Over many bets you would expect to make about 9.2% of your total stakes.

Break-even probability and edge

Every price has a break-even probability: 1 divided by the decimal odds. At 2.10 that is 47.6%. Your edge is your own probability minus that number, in percentage points. At 52% the edge is 4.4 points. A positive edge is the same thing as a positive EV.

Try your own numbers in the free EV calculator, which also shows the fair odds for your probability.

Why a positive EV bet can still lose

EV is an average over many bets, not a promise about the next one. A bet with a 52% chance loses 48 times in 100. Results swing a lot over small samples, which is why we publish every settled pick, wins and losses, on the Track Record page.

The catch: your probability is an estimate

The formula is exact, but the input is not. If you estimate 52% and the true chance is 47%, the bet was never positive. Bookmaker odds also include a margin, so the implied probability of all outcomes adds up to more than 100%. Strip that margin first to see the fair probability behind a price.

How Vantip uses it

Vantip shows an edge on its picks: the model's confidence minus the bookmaker's de-vigged probability. It is an estimate, not proof of value, and the limits are explained on Tips Explained. Past results do not guarantee future results. 18+. Please gamble responsibly.