Kelly Criterion Bet Size Calculator
Calculate optimal bet size using the Kelly Criterion formula to maximize long-term growth
About this calculator
The Kelly Criterion Bet Size Calculator helps determine the optimal percentage of your bankroll to wager on any given bet to maximize long-term wealth growth. Developed by mathematician John Kelly Jr., this formula balances risk and reward by considering your win probability and potential payout odds. By using this calculator, bettors and investors can avoid over-betting while ensuring they're not being overly conservative, leading to optimal capital growth over time while minimizing the risk of bankruptcy.
How to use
Enter your estimated win probability as a percentage, input the odds you're receiving on your bet, and specify your current bankroll amount. The calculator will instantly compute the optimal bet size using the Kelly formula: (bp - q) / b, where b is the odds, p is win probability, and q is loss probability.
Frequently asked questions
What happens if the Kelly Criterion suggests betting more than I'm comfortable with?
Many experienced bettors use fractional Kelly (like half-Kelly) to reduce volatility while still benefiting from optimal sizing principles.
Can the Kelly Criterion result in negative bet sizes?
Yes, negative results indicate the bet has negative expected value and should be avoided entirely according to the formula.
Is the Kelly Criterion suitable for all types of betting?
Kelly works best for repeated bets with known probabilities and odds, making it ideal for sports betting and investing scenarios.