Position Size Calculator: Kelly Criterion

Full Kelly, half-Kelly, and quarter-Kelly position sizes from your edge estimate, with an honest drawdown warning.

Win probability p

Average win ($) per unit risked

Average loss ($) per unit risked

Bankroll ($)

Calculating…

Long-run growth per bet vs. the fraction of full Kelly wagered. Markers show full, half, and quarter Kelly.

Assumption check

The Kelly criterion maximizes long-run compounded growth if you know your win probability and payoff odds. You never know them exactly, hence fractional Kelly.

The Investor Stats Cheat Sheet

A free three-page PDF: breakeven win rates, stop-loss sizing, volatility drag, reverse valuation, and how to tell a real track record from noise. Plus new tools as they ship.