Position Sizing Calculator

Calculate optimal position size using Kelly Criterion for maximum edge

Your Trading Stats

Your total trading capital

Percentage of winning trades (e.g., 65%)

Average profit per winning trade

Average loss per losing trade

Current option premium per contract

Maximum % of account to risk (usually 1-2%)

Quick Presets:

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Enter your trading stats and click Calculate

What is Kelly Criterion?

Kelly Criterion is a mathematical formula that tells you the optimal % of your account to risk on each trade to maximize long-term growth. It factors in your win rate and average win/loss ratio.

How to Use This:

  • Track your last 30+ trades to get accurate win rate and R:R
  • Start with Half Kelly until you prove your edge over 100+ trades
  • If Expected Value is negative, DO NOT TRADE - fix your strategy first
  • Recalculate monthly as your stats improve
  • Never risk more than 2-3% of account per trade (even if Kelly says more)