Part III: Business & Regulation · Gambling Mathematics & Probability

60. Risk of Ruin

Risk Management

Risk of ruin is the mathematical probability that a gambler will lose their entire bankroll (or reach a point where they cannot continue playing) before their positive expected value manifests as actual profit. Even with a mathematical edge, risk of ruin is never zero if bets are sized too aggressively relative to bankroll. The simplified formula for risk of ruin with fixed bet sizes is: ROR = (q/p)^(B/b), where p is the win probability, q is the loss probability, B is the bankroll, and b is the bet size. For continuous bankroll adjustment (Kelly criterion), risk of ruin theoretically approaches zero over time. Casino surveillance is primarily concerned with risk of ruin from the operational perspective — ensuring the house maintains sufficient reserves to cover variance and large jackpot payouts.

In practice

A player with a 1% edge, $10,000 bankroll, and $100 average bet has a risk of ruin of approximately 1-2%. Increasing the bet size to $200 raises ROR to roughly 10-15%. Casinos face operational risk of ruin from progressive jackpot exposure, which is why large progressives are often centrally funded or insured.

One entry from the Casino Industry Glossary — 1,157 terms written for surveillance, compliance and operations professionals rather than for players. Definitions describe industry usage; where a term carries a regulatory meaning, verify against the instrument that governs your jurisdiction.