Blackjack Card Counting Bankroll Risk Calculator

This educational tool estimates the statistical risk of ruin for a given bankroll, edge, and average bet size using a standard risk-of-ruin approximation formula used in probability and game theory study.

Estimated Risk of Ruin
Bankroll in Betting Units
Player Edge (%)
Bet Variance (SD units)
Estimated Risk of Ruin (%)

About this calculator

Estimate the risk of ruin and recommended bankroll size for advantage-based betting spreads using bet size, edge, and bet variance inputs — for educational and strategy study purposes.

Frequently Asked Questions

What is risk of ruin?

Risk of ruin is the statistical probability that a bankroll will be depleted to zero before achieving sustained long-term growth, based on edge, bet size, and variance.

Why does a negative edge always result in 100% risk?

If the average expected value per bet is negative, a large enough number of bets will mathematically exhaust any finite bankroll over the long run.

Is this calculator for real-money gambling decisions?

No, this tool is intended for educational exploration of probability and risk formulas used in game theory and statistics, not as gambling advice.