Blackjack Risk of Ruin Calculator
Calculate the probability of losing your entire bankroll
Formula:RoR = e^(-2 × Edge × Units / Variance)
Bankroll Analysis
Enter your bankroll, bet size, and edge
Card counter: 0.5% to 1.5% | Basic strategy: -0.5%
Blackjack is typically 1.1 to 1.2 per hand
Low Risk - Well Capitalized
Risk of Ruin
0.00%
Survival Rate: 100.00%
Betting Units
100.0
Your Edge
+1%
Bankroll
$10,000
Avg Bet
$100
Recommended Bankroll for Target RoR
1% RoR
$30,452
305 units
5% RoR
$19,810
199 units
10% RoR
$15,226
153 units
Example Scenarios
Compare different bankroll situations
Bankroll Simulation
Monte Carlo simulation with 1,000 iterations
$
Your initial capital
%
Your expected advantage
%
Percentage of bankroll per bet
Total bets to simulate
Quick Answer
Key concepts at a glance
Risk of ruin is the probability of losing your entire bankroll before reaching your goal. With a 1% edge, $10,000 bankroll, and $100 average bet (100 units), your RoR is about 5%. Reducing bet size or increasing bankroll dramatically lowers RoR. Card counters typically aim for 5% or lower RoR. Recreational players with no edge face eventual certain ruin.
Key Facts About Risk of Ruin
Critical bankroll management knowledge
- Risk of ruin decreases exponentially as bankroll (in betting units) increases
- A 1% edge with 100 betting units gives roughly 5% RoR
- Without an edge, RoR is 100% - you will eventually lose everything
- With $200 average bet on $10,000 bankroll (50 units) and 1% edge, RoR is ~22%
- Professional counters typically maintain 200-400 betting units minimum
- The Kelly Criterion suggests betting (edge / variance) of bankroll
- Doubling bet size roughly quadruples risk of ruin
Frequently Asked Questions
Common questions about risk of ruin
What is risk of ruin in blackjack?
Risk of ruin (RoR) is the probability that you will lose your entire bankroll before achieving a specified goal (or before quitting). With a $10,000 bankroll, 5% RoR means there's a 5% chance of going broke before winning significantly. This assumes continuous play with no withdrawals or reloads.
How many betting units do I need?
The standard recommendation for card counters is 200-400 betting units. With a $25 minimum bet and 1:8 spread ($200 max), if your average bet is $50, you need $10,000-$20,000 bankroll. More units = lower RoR. 100 units gives roughly 5% RoR with 1% edge.
Why does variance matter for risk of ruin?
Blackjack has high variance (standard deviation ~1.15 per hand). Even with an edge, you can experience long losing streaks. High variance means you need a larger bankroll to survive the swings. Variance from splits, doubles, and blackjack bonuses all contribute to the rollercoaster.
What edge do card counters typically have?
Skilled card counters typically achieve 0.5% to 1.5% edge over the house. A 1% edge is a reasonable estimate for a good counter with decent rules and penetration. Higher spreads increase edge but also increase variance and heat from the casino.
Can recreational players have a positive edge?
No, without card counting or exploiting specific promotions, recreational players face a house edge of 0.5% or more. This means RoR is effectively 100% given enough time. Bankroll management only affects how long you can play, not the eventual outcome.
How this works
Calculations follow the published mathematics of the game — combinatorics for cards, probability theory for dice, and expected-value accounting for wagers. Results are verified against independent references (primarily Wizard of Odds). No calculation here is an opinion or recommendation; it is arithmetic applied to the rules of the game.
What this tool can’t do
When to consult a professional
This tool computes probability and expected value. It is not a betting system and cannot predict the outcome of any individual wager. If gambling is causing problems for you or someone you know, call the National Problem Gambling Helpline at 1-800-GAMBLER.
Sources
- [1]Wizard of Odds — Michael Shackleford, ASAIndustrywizardofodds.comAccessed Apr 21, 2026
Actuary; widely cited casino-game probability reference. Used for house-edge and EV verification.
- [2]National Council on Problem GamblingOfficial sourcencpgambling.orgAccessed Apr 21, 2026
Responsible-gambling guidance and 1-800-GAMBLER helpline.
Joseph OrdunaFounder & Software Engineer
Full-stack software engineer specializing in embedded systems, web architecture, and AI/ML. Founder of Practical Web Tools. Built the gesture-controlled drone IP acquired by KD Interactive (Aura Drone, sold on Amazon).