Expected Value (EV) Calculator

Expected value (EV) is the average amount you expect to win or lose per bet over the long run. Positive EV (+EV) means you have an edge; negative EV (-EV) means the house has the edge.

Formula: EV = (True Probability x Profit) - ((1 - True Probability) x Stake)

The key insight: You need to know the true probability of an outcome, not just the market odds. This is where models like Elo ratings come in—they give you an independent probability estimate to compare against the market.

Kelly Criterion tells you the optimal percentage of your bankroll to wager on a +EV bet. It maximizes long-term growth while managing risk.

Formula: Kelly % = (b x p - q) / b, where b = decimal odds - 1, p = true probability, q = 1 - p

In practice: Most sharp bettors use fractional Kelly (25-50% of the suggested amount) to reduce variance. A 10% Kelly suggestion might translate to a 2.5-5% actual bet size.