Position sizing from win probability and reward:risk.

Kelly Criterion Position Sizing

Turn a win probability and reward:risk estimate into a disciplined position size, instead of sizing by feel.

Win Probability

Reward : Risk

Portfolio Size (optional)

Full Kelly

40.0%

Exceeds typical single-position risk limits.

Half Kelly

20.0%

Quarter Kelly

10.0%

Full Kelly assumes your win-probability and reward:risk estimates are exactly correct, which real-world estimation error makes unlikely — half or quarter Kelly is standard institutional practice. This is a sizing framework, not investment advice.