Kelly Criterion Calculator
The Kelly Criterion estimates a bankroll fraction from your odds and projected win probability. Full Kelly maximizes theoretical long-run logarithmic growth when the inputs are correct, but probability errors can make it dangerously aggressive. Half- or quarter-Kelly reduces volatility and estimation risk; never stake money you cannot afford to lose.
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The Kelly Criterion is a formula for optimal bet sizing: it tells you what fraction of your bankroll to risk when you have an edge. This calculator gives full Kelly, half Kelly, and quarter Kelly suggestions so you can balance growth with risk.
Pair it with bankroll management principles—many bettors use half- or quarter-Kelly to reduce variance while still growing their edge over time.
Kelly Criterion Calculator
Frequently asked questions
Should I use full Kelly?
Full Kelly can be highly volatile and sensitive to estimation errors, so many bettors use half- or quarter-Kelly.
Can Kelly recommend no bet?
Yes. A zero or negative Kelly fraction means the supplied probability does not beat the available price.
What bankroll should I enter?
Use a dedicated betting bankroll you can afford to lose, not savings or money needed for expenses.