What is the Kelly criterion?

The Kelly criterion is a staking formula that sizes bets based on your edge and bankroll to maximize long-run growth.

Should I use full Kelly stakes?

Many traders use half-Kelly or smaller fractions to reduce volatility and drawdowns.

What probability should I enter?

Use your estimated win chance, not the market implied probability, to capture your true edge.

Kelly Staking Calculator

Use your estimated edge to size stakes responsibly. The Kelly criterion suggests a bankroll fraction that maximizes growth while managing risk.

Calculate a stake size from your bankroll.
Adjust for your estimated win probability.
Compare full Kelly to more conservative staking.

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Kelly Staking Calculator

Size stakes using the Kelly criterion based on your estimated edge.

Bankroll management

Kelly staking links your edge to your stake size. When you believe you have a strong edge it suggests staking more; when your edge is small it recommends reducing stakes. Many traders use half-Kelly or smaller fractions to control drawdowns and avoid aggressive swings in bankroll.

How it works

How the calculation works

Core formula: f* = (b·p − q) / b where b = odds − 1, q = 1 − p

Worked example: Bankroll £1,000, odds 2.5, win chance 45%.

b = 1.5, p = 0.45, q = 0.55.
f* = (1.5 × 0.45 − 0.55) ÷ 1.5 = 0.0833.
Stake = 0.0833 × £1,000 = £83.33 (full Kelly).

Always gamble responsibly. This calculator is for information only and does not guarantee profit.

FAQs

Is Kelly staking aggressive?

Full Kelly can be aggressive. Many traders choose half-Kelly or lower to manage drawdowns.

What if my estimated probability is wrong?

Overestimating your edge can lead to over-staking. Use conservative inputs if unsure.

Can I use Kelly for exchange trading?

Yes. Enter your odds, bankroll and probability to estimate a stake size for exchange bets.