Bankroll Simulator
Run Monte Carlo simulations to visualize how variance affects your bankroll over time. Understand risk of ruin, optimal bet sizing, and why even with perfect play, short-term results can vary wildly.
⚙️ Simulation Parameters
Configure your simulation settings. Use presets for common casino games or enter custom values.
Ready to Simulate
Configure your parameters above and click "Run Simulation" to see results
Understanding Monte Carlo Simulation for Gambling
Monte Carlo simulation is a computational technique that uses random sampling to understand the behavior of complex systems. Named after the famous casino in Monaco, it's particularly apt for analyzing gambling outcomes. Instead of trying to predict a single result, Monte Carlo simulation runs thousands of possible scenarios to show you the full range of outcomes you might experience, as documented in research from the Journal of Computational Mathematics.
When you gamble, each session's outcome is influenced by two factors: the mathematical edge (house advantage) and random variance. While the house edge determines long-term results, variance creates the wild swings you experience in any given session. This simulator helps you visualize both effects.
What is Risk of Ruin?
Risk of ruin (RoR) is the probability of losing your entire bankroll before achieving a goal or ending your session. It's one of the most important concepts in bankroll management, studied extensively in both gambling theory and financial mathematics. According to gambling mathematics research from the UNLV International Gaming Institute, understanding risk of ruin is essential for anyone engaged in any form of wagering.
Your risk of ruin depends on three main factors:
- House Edge: Higher house edge means faster bankroll erosion on average
- Bet Size Relative to Bankroll: Larger bets = higher variance = higher risk of ruin
- Session Length: More bets give variance more opportunities to push you to zero
Bet Sizing and Bankroll Management
One of the most powerful insights from Monte Carlo simulation is understanding how bet sizing affects survival. The table below shows typical risk of ruin percentages for different bet-to-bankroll ratios, based on principles from the Kelly Criterion, a formula developed by mathematician John Kelly at Bell Labs.
| Bet Size (% of Bankroll) | Risk Profile | Typical RoR (100 bets, 2% edge) | Recommended For |
|---|---|---|---|
| 1% | Conservative | ~5% | Long sessions, bankroll preservation |
| 2% | Moderate | ~12% | Balanced approach |
| 5% | Aggressive | ~28% | Short sessions, entertainment focus |
| 10% | Very High Risk | ~52% | Not recommended |
| 25% | Extreme Risk | ~85% | Virtually guaranteed to bust |
Key Insight: Many gamblers bet far too large relative to their bankroll. Betting 10% of your bankroll per bet gives you roughly a coin-flip chance of going bust within 100 bets, even on low-edge games.
How to Use This Simulator
This tool helps you explore different gambling scenarios before risking real money:
- Set Your Parameters: Enter your bankroll, bet size, and the game's house edge. Use presets for common casino games.
- Run the Simulation: The tool runs 1,000+ independent sessions, each simulating your specified number of bets.
- Analyze Results: See your risk of ruin, average/median outcomes, and the distribution of possible results.
- View Sample Paths: The chart shows 10 random session paths to visualize how bankrolls evolve over time.
Interpreting the Results
Risk of Ruin
The percentage of simulations where you lost your entire bankroll before completing all bets. Higher is worse. If this number is above 20%, consider reducing your bet size.
Median vs Average Outcome
The median (middle value) is often more representative than the average. A few big wins can skew the average upward, but the median tells you what a "typical" session looks like. Our house edge calculator can help you understand expected losses.
Outcome Distribution
The colored bar shows what percentage of sessions ended in each category. Even with a house edge against you, some sessions will end in profit—that's variance. But over many sessions, the house edge wins out.
Important: This simulator shows theoretical results based on fair, random outcomes. It does not guarantee real-world results. Gambling involves real financial risk. Never gamble with money you cannot afford to lose. For responsible gambling resources, visit our responsible gambling guide.
The Mathematics Behind the Simulation
Each bet in the simulation is resolved using a random number generator that respects the game's true probability. For an even-money bet with a 2.7% house edge (like European roulette):
- Win probability: 48.65% (18/37)
- Loss probability: 51.35% (19/37)
The simulation generates a random number between 0 and 1. If it's below the win probability, you win; otherwise, you lose. This process repeats for every bet in every simulation, creating thousands of possible session outcomes that collectively reveal the true range of possibilities.
For more on probability theory in gambling, see our probability calculator and our guide on why betting systems don't work.
Frequently Asked Questions
What is a Monte Carlo simulation in gambling?
A Monte Carlo simulation uses random sampling to model the probability of different outcomes. In gambling, it simulates thousands of betting sessions to show the range of possible results, helping you understand how variance affects your bankroll over time. The technique is named after the Monte Carlo Casino in Monaco.
What is a safe bet size for my bankroll?
Most gambling experts recommend betting no more than 1-2% of your bankroll per bet for recreational play. This allows you to survive short-term variance and extend your playing time. Betting 5%+ per bet significantly increases your risk of ruin, especially over longer sessions.
Why do my results vary so much between simulations?
That's variance in action! Each simulation run generates new random outcomes. While individual runs vary, the overall statistics (average outcome, risk of ruin) should be similar across runs when you use enough simulations (1000+). This mirrors real gambling—every session is different.
Can this simulator help me win at gambling?
No simulator can help you overcome the house edge. What this tool does is help you understand the mathematical reality of gambling. It shows that even with variance on your side in the short term, the house edge will prevail over time. Use it to set realistic expectations and practice responsible bankroll management.