Back to path GUIDEBOOKKelly Sizing
UNIT 3

Kelly Criterion

Kelly maximizes long-run logarithmic wealth when probabilities and payoffs are known.

Full KellyMax growthHigh volatility
What it tells you

A theoretical upper sizing reference for a repeatable edge.

When it is useful
  • Comparing bet sizes
  • Understanding overbetting
When it fails
  • Inputs are estimated
  • Full Kelly can have severe drawdowns
COMMON MISTAKE

Treating a fragile edge estimate as a known probability.

Evidence note

Kelly's mathematical result is exact under its assumptions; real-world inputs rarely are.

60-SECOND CHEAT SHEET

Remember this.

  1. 1f* = (bp − q) ÷ b
  2. 2Over Kelly reduces growth
  3. 3Estimate error matters
NEXT ACTIVITYSize the BetTurn edge and payoff into a practical fraction.
Try it now