Kelly Criterion Calculator

Calculate optimal bet sizing using the Kelly Criterion for maximum long-term bankroll growth.

Your total available betting bankroll.
The decimal odds offered by the bookmaker (e.g. 2.50 means +150 American).
Your estimated true probability of winning. Must be higher than implied probability for a positive edge.
Formula: f* = (bp - q) / b, where b = decimal odds - 1, p = win probability, q = 1 - p. Full Kelly maximizes long-term growth but has high variance. Half Kelly and Quarter Kelly reduce variance at the cost of slightly lower growth. The expected growth rate per bet = p * ln(1 + f*b) + q * ln(1 - f*).