Gambling terms, explained straight

Odds, Probability & Bankroll

Risk of ruin blackjack

Risk of ruin in blackjack is the probability that a player's bankroll drops to zero, or below the minimum needed to continue, before the session or goal is reached.

Example house edge
0.4140% for the referenced ruleset1
Example bankroll
102 units gives a risk of ruin just over 0.01%1
Team risk levels
MIT Blackjack Teams played to about 2–3% risk of ruin; more aggressive teams to 5%3

Key points

  • Risk of ruin estimates the chance that short-term variance depletes a bankroll before the player's edge can be realised over many bets.2
  • Higher betting aggressiveness raises the probability; a larger bankroll or smaller bets reduce it.3
  • The calculation is typically framed for flat betting or for bankroll/edge models with a specified variance and betting schedule.2

Where this term is used

Odds & probability Risk of ruin The general concept of the probability of going broke, applied across gambling contexts. Odds & probability Blackjack house edge The mathematical advantage the casino holds over a blackjack player. Odds & probability Risk vs odds How risk (probability of loss) differs from odds (ratio of payout to stake). Odds & probability Martingale system blackjack A betting system that doubles after a loss, which increases risk of ruin. Odds & probability Bankroll management blackjack Strategies for sizing bets to control risk of ruin in blackjack. Odds & probability Kelly criterion blackjack A formula for optimal bet sizing that balances growth and risk of ruin.

Sources

  1. Risk of Ruin in blackjack wizardofodds.com Provides the example house edge and bankroll unit figures for risk of ruin in blackjack.
  2. Variance and Bankroll Management for Player Props wizardofodds.com Explains the formula and concept of risk of ruin in relation to variance and edge.
  3. How to Determine a Betting Strategy - Wizard of Odds wizardofodds.com Gives the MIT team risk of ruin percentages and the effect of betting aggressiveness.

Sources are drawn from regulators, universities and published research, and each one is labelled with what it actually is — a preprint is not called a paper. Bookmaker and affiliate pages are never cited here, because a page that sells betting is not a neutral authority on it.

Written and maintained by Ellis Warrender, writer and maintainer.

Last updated 28 July 2026. Spotted an error? Tell me and it gets fixed and logged on the corrections page.