Calculate optimal bet sizing based on your edge
Use Half Kelly for a safer approach with good growth. Full Kelly maximizes growth but increases variance significantly.
Kelly % = (bp - q) / b
Where:
• b = decimal odds - 1 (net odds)
• p = your probability of winning
• q = probability of losing (1 - p)
Full Kelly can be too aggressive. Half Kelly provides:
• 75% of the growth rate
• 50% of the variance (risk)
• Better protection against estimation errors
Kelly assumes you know your true edge. If you overestimate your probability, you'll over-bet and lose money faster. Always be conservative with your estimates.
| Edge | Full Kelly | Half Kelly | Risk Level |
|---|---|---|---|
| 1-2% | 1-3% | 0.5-1.5% | 🟢 Low |
| 3-5% | 4-8% | 2-4% | 🟡 Moderate |
| 6-10% | 10-20% | 5-10% | 🟠 High |
| 10%+ | 20%+ | 10%+ | 🔴 Very High |
Most professional bettors cap their bets at 2-3% of bankroll regardless of Kelly output. High Kelly percentages often indicate overconfidence.