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 to maximize the logarithm of wealth. It was formulated by John L. Kelly Jr. while working at Bell Labs in 1956.

The Kelly strategy involves betting a percentage of your bankroll based on the perceived edge you have in a wager. It aims to maximize the long-term growth rate of your bankroll while minimizing the risk of ruin.

This calculator helps you determine the optimal stake size as a percentage of your bankroll based on the odds and your estimated probability of winning.

Calculate the optimal stake as a percentage of your bankroll.

Bankroll (Optional)

Enter your total bankroll to calculate the recommended stake amount.

Odds Format

Decimal Fractional American

Bookmaker Odds

Enter the odds offered by the bookmaker.

Your Estimated Probability (%)

Enter your estimated probability of winning (between 0% and 100%).

Kelly Fraction (%)

Many professional bettors use a fraction of the Kelly stake (e.g., 50%) to reduce variance.

Kelly Criterion Results

Full Kelly Stake (%)

12.50%

of your bankroll

Bookmaker Implied Probability

55.56%

Your Edge

4.44%

Kelly Criterion Tips

Use fractional Kelly - Most professional bettors use only a fraction (typically 25% to 50%) of the full Kelly stake to reduce variance.
Be conservative with probabilities - It's very easy to overestimate your edge. Be as objective as possible when estimating probabilities.
Consider the variance - Kelly optimizes for long-term growth but can lead to significant short-term fluctuations.
Define your bankroll carefully - Only count funds that you're willing to use specifically for betting.
Never exceed the Kelly stake - Betting more than the Kelly recommendation increases your risk of ruin without improving your growth rate.

Kelly Criterion Calculator

What is the Kelly Criterion?