Kelly Criterion Calculator

Quick Facts

  • Computes optimal stake fraction (Kelly %).
  • Inputs: bankroll, odds, win probability.
  • Outputs: Kelly %, amount, half-Kelly, EV%.

How to use

Steps

Add bankroll, your price, and win probability. Read Kelly % and amount; consider half-Kelly for a conservative approach.

Formula & definitions

Formula: Kelly = (b·p − (1 − p)) / b, where b = (odds − 1)

Kelly Fraction
Stake % that maximises long-term growth.
Half-Kelly
Conservative variant to reduce variance.
Try also: Arbitrage · EV · Implied Probability

Kelly Criterion Calculator

Kelly %
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Kelly Bet
0.00
½ Kelly Bet
0.00
Expected Value %
0.00%

What is the Kelly Criterion? [Optimal Staking]

The Kelly Criterion is a legendary bankroll management formula that tells you exactly how much to stake to maximize long-term growth—while minimizing your risk of ruin. It's the gold standard for professional punters, investors, and +EV bettors worldwide.

How Does Kelly Work?

  • Enter your bankroll, the odds (any format), and your estimated probability of winning.
  • The calculator outputs the optimal bet size as a % of your bankroll (Kelly %) and in cash units.
  • Kelly stakes maximize long-term growth but can be aggressive—many experts use a fractional Kelly (e.g., half Kelly) for more conservative risk management.
  • Expected value (EV) is shown, so you can quickly see if your edge is positive.

Why Use Kelly? [Benefits & Strategy]

  1. Always stake in line with your real edge—never overbet or underbet.
  2. Helps avoid blowing your bankroll on variance or short-term swings.
  3. Simple, quick, and perfect for high-frequency betting or investing.
  4. Backtested and used by world-class sports bettors and financial pros.
Tip: Only use the Kelly Criterion when you have a proven edge and an honest estimate of your win probability. Unsure? Use a more conservative (fractional) Kelly for safety.
Need help converting odds? Try the Implied Probability Calculator.