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 two-page PDF: expected value, Kelly sizing, Sharpe, sample-size math, and how to read a p-value without fooling yourself. Plus new tools as they ship.