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For information and entertainment only — not betting, financial or legal advice. Results are estimates based on your inputs.
How the Kelly Criterion Calculator works
The Kelly criterion gives the share of a bankroll that maximises long-run growth when you know your true edge. Because real-world probabilities are estimates, a fraction of the full Kelly stake is far more common. If there is no edge, the answer is zero.
Formula
- Kelly fraction f* = (b × p − q) ÷ b
- b = decimal odds − 1, p = win probability, q = 1 − p
- Stake = bankroll × f* × chosen fraction
Worked example
At 2.10 odds and a 52% estimate, b = 1.10, f* = (1.10 × 0.52 − 0.48) ÷ 1.10 = 8.4% of bankroll. Half Kelly is 4.2% — 42 on a 1,000 bankroll.
Frequently asked questions
Is full Kelly safe?
Full Kelly is very aggressive and produces large swings, and it assumes your probability is exactly right. Overestimating your edge can lead to over-betting.
Play responsibly
Calculators describe maths, not outcomes. Gambling is for adults aged 18+ and can be addictive — set limits and never stake money you cannot afford to lose.