📐 Kelly Criterion Calculator

Find the mathematically optimal position size to maximize long-term growth of your trading capital.

How to Use the Kelly Criterion Calculator

  1. Enter your win rate — Historical percentage of winning trades
  2. Average win — Mean profit per winning trade
  3. Average loss — Mean loss per losing trade
  4. Total capital — Your current trading account balance
  5. Click Calculate — Get optimal position sizing

What is the Kelly Criterion?

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

Formula: Kelly % = (bp - q) / b

  • b = win/loss ratio
  • p = probability of winning
  • q = probability of losing (1 - p)

Why Use Half Kelly?

Most professional traders use Half Kelly or even Quarter Kelly because:

  • Full Kelly is mathematically optimal but extremely volatile
  • Half Kelly gives ~75% of the growth with ~50% of the drawdown
  • It provides a psychological buffer for estimation errors

Key Warning

The Kelly Criterion assumes your win rate and win/loss ratio are accurate and stable. Overestimating either leads to dangerous over-sizing.

Risk Disclaimer

CFD trading involves significant risk. Past performance does not guarantee future results. Use Kelly sizing as a guide, not an absolute rule.

Smart position sizing needs a broker with flexible lot sizes. UZFX — micro lots from 0.01, minimum deposit just $10.