Kelly Criterion Calculator

What is the Kelly Criterion?

The Kelly Criterion is a mathematical formula used to determine the optimal size of a series of bets. In sports betting, it helps you maximize the long-term growth of your bankroll by balancing the size of your edge against the risk of ruin.

The Formula:
f* = (bp - q) / b
  • f*: The fraction of the bankroll to wager.
  • b: The decimal odds minus 1 (net odds).
  • p: The probability of winning (0.0 to 1.0).
  • q: The probability of losing (1 - p).
Why use Half-Kelly? While Full Kelly maximizes growth, it is extremely volatile. Most professional bettors use "Half-Kelly" to provide a safety buffer against inaccurate probability estimates.