Calculator
Kelly Criterion
Find the mathematically optimal stake size based on your edge and the available odds. Maximizes long-run bankroll growth while avoiding over-betting.
Enter your win probability and the available odds to calculate
Recommended stake
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Dollar amount to bet
Expected value
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Per $100 wagered
How Kelly works
- Win probability
- Your honest estimate of the true chance this bet wins. This is the hard part — Kelly is only as good as your probability estimate.
- Kelly formula
- f = (bp - q) / b where b = decimal odds - 1, p = win probability, q = 1 - p. Result is the fraction of bankroll to bet.
- Half Kelly
- Most professionals use Half Kelly (bet 50% of the Kelly recommendation) to reduce variance while keeping most of the growth benefit.
- Negative Kelly
- If Kelly returns a negative number, the bet has negative expected value — you should not bet at all at those odds.