📈

Kelly Criterion Calculator

Optimize your bet sizing using the Kelly formula for maximum growth.

📋 How to Use

  1. 1 Enter your estimated win probability (0-100%)
  2. 2 Enter the win odds (e.g., 2.0 means you win 2x your bet)
  3. 3 Enter the loss odds (usually 1.0, meaning you lose your bet)

⚠️ Risks & Warnings

  • • Full Kelly can be very aggressive and lead to large drawdowns
  • • Overestimating win probability leads to overbetting and potential ruin
  • • Many professionals use "Half Kelly" or "Quarter Kelly" for safety
  • • Never bet more than you can afford to lose

📚 What is Kelly Criterion?

The Kelly Criterion is a mathematical formula used to determine the optimal size of a series of bets to maximize long-term growth. Developed by John L. Kelly Jr. at Bell Labs in 1956.

🎯 Understanding the Result

A Kelly fraction of 0.25 means you should bet 25% of your bankroll. Negative values mean the bet has negative expected value - do not bet. Values over 1.0 are rare and suggest reviewing your inputs.

💡

Expert Note

Pro Tip: Most experienced bettors use Half Kelly (divide result by 2) to reduce volatility while maintaining good growth.

📊

Formula

Kelly Criterion formula: f* = (bp - q) / b, where b is the odds, p is win probability, and q is loss probability (1-p).