Kelly Criterion Calculator

The Kelly Criterion is a formula that calculates the optimal percentage of your bankroll to wager. It maximizes long-term bankroll growth while avoiding ruin. Formula: f* = (bp − q) / b, where b = decimal odds − 1, p = win probability, q = 1 − p.

Almost never. Full Kelly is extremely aggressive and leads to huge swings. Most sharp bettors use quarter Kelly (25%) or half Kelly (50%). This sacrifices some theoretical growth for dramatically lower variance and risk of ruin.

If the Kelly formula returns zero or negative, it means you don't have an edge at those odds. Either your estimated probability is too low for the price, or you shouldn't be betting that market.