Kelly Criterion Educational Calculator

Six-step workflow

1. Copy current values from the official account, platform, or journal.
2. Keep every unit consistent; do not mix ticks, points, pips, dollars, or percentages.
3. Enter the planning assumptions without changing them to force a preferred answer.
4. Calculate and read every output, including the warning below the headline number.
5. Verify instrument specifications and binding firm rules at the official source.
6. Save the result with its date and compare it with what actually happened.

Understand the output

Formula: Kelly fraction = (payoff ratio × win probability − loss probability) ÷ payoff ratio.

Worked example: At 45% wins and 1.5:1 payoff, full Kelly is about 8.33%. A 25% fraction is 2.08%, then the entered personal cap can reduce the display further.

Common mistakes: using small-sample estimates, applying full Kelly, ignoring tail losses, and treating the output as advice.