What Are Risk of Ruin and the Kelly Criterion?
Risk of Ruin is the mathematical probability of losing your entire bankroll given your win rate, variance (standard deviation), and current bankroll size. Even a solidly winning player can go broke playing stakes too high for their roll — short-term variance alone is enough. That's why professionals treat bankroll management as seriously as playing skill.
The Kelly Criterion tells you the optimal fraction of your bankroll to risk in order to maximize long-term growth. This calculator combines both metrics and recommends the blind level you can safely play with your current bankroll.
How to Use
- Enter your win rate (bb/100 or hourly). If you don't know it yet, track your sessions with My Bankroll to measure it.
- Enter your standard deviation. Typical no-limit hold'em cash games run around 80–120 bb/100.
- Enter your current bankroll and the stake you play.
- Review your risk of ruin and the recommended stakes — keep your risk of ruin under 5% by moving stakes up or down.
Frequently Asked Questions
What risk of ruin percentage is acceptable?
Most professionals recommend staying under 1–5%. If your risk of ruin exceeds 10%, that's a warning sign to move down in stakes or top up your bankroll. If poker is your main income, a stricter threshold under 1% is safer.
What is the Kelly Criterion?
A formula that computes what fraction of your bankroll to risk to maximize long-term growth, based on your edge and variance. Because poker variance is high, most players use half-Kelly rather than full Kelly for an extra margin of safety.
How many buy-ins do I need for cash games?
A common guideline is 20–50 buy-ins for cash games and 100–200 for tournaments, whose variance is far higher. The right number depends on your personal win rate and standard deviation — this calculator computes it from your own data.