The Kelly Criterion is a formula for calculating the optimal betting/investment ratio to maximize long-term wealth.
Formula: f* = (bp - q) / b
f* = Optimal investment ratio
b = Odds (net return rate)
p = Win probability
q = Lose probability (1-p)
Probability of winning (0-100%)
Amount received on 100 bet if you win (e.g., 200 = 2.0 odds)
Enter your bankroll to see recommended bet amount
Kelly Ratio
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Recommended Bet
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Kelly Variants
Full Kelly (100%)
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Half Kelly (50%)
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Quarter Kelly (25%)
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Notes
- Full Kelly: Mathematically optimal but high volatility
- Half Kelly: Commonly used in practice, 75% less volatility
- Negative result: Don't bet (negative expected value)
- Kelly Criterion is only valid when probability and odds are accurate