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Betting Variance Simulator
Visualize betting variance with Monte Carlo simulation. Understand expected drawdowns, risk of ruin, Kelly-optimal sizing, and the psychological challenges of sports betting through thousands of simulated scenarios.
Bankroll Settings
Your Edge
Simulation
Configure your settings and click "Run Simulation"
to visualize variance and drawdowns
Understanding Betting Variance
Variance is the natural fluctuation in results that every bettor experiences, regardless of their edge. Even profitable bettors will experience significant drawdowns – periods where their bankroll drops substantially from its peak.
Why This Matters
- • A 53% win rate at -110 is profitable long-term
- • But you WILL experience 10+ game losing streaks
- • 30%+ drawdowns are common, even with an edge
- • Most bettors quit during normal variance
Key Takeaways
- • Use small unit sizes (1-3%) to survive variance
- • Have a bankroll you can afford to lose
- • Trust the process during drawdowns
- • Track results to verify your actual edge
This calculator is for informational and educational purposes only. Results should be verified with your sportsbook before placing any wagers. All betting carries risk. Full Disclaimer
How to Use This Calculator
- 1Set your bankroll and unit size: Enter your starting bankroll and the percentage you bet per wager.
- 2Enter your edge: Input your true win rate and the average American odds you bet at so the model knows your expected value.
- 3Choose the sample size: Set how many bets to simulate and how many full simulations to run (e.g. 500 bets x 1000 sims).
- 4Run and read the variance: Click Run Simulation to see profit probability, risk of ruin, expected drawdowns, and Kelly-optimal sizing.
Frequently Asked Questions
What is a betting variance simulator?
It's a Monte Carlo tool that plays out thousands of betting seasons using your win rate, odds, and unit size. Instead of a single expected-value number, it shows the full range of realistic outcomes, including drawdowns and bust risk you'll actually experience.
What is risk of ruin in sports betting?
Risk of ruin is the probability of losing your entire bankroll before the math plays out. It rises sharply with larger unit sizes, even when you have a real edge. This simulator reports your bust risk and the chance of 20%+ and 50%+ downswings.
How big should my unit size be?
The Kelly Criterion gives the growth-optimal unit: f* = (b·p − q) / b, where b is your decimal profit, p your win rate, and q your loss rate. Most bettors use half Kelly or less to cut variance roughly in half while keeping most of the long-term growth. The simulator computes both for your inputs.
Can I go broke even with a winning record?
Yes. A 53% win rate at -110 is profitable long-term, but oversized units combined with a normal losing streak can still bust you. That's the core lesson of this simulator: edge alone doesn't protect you — sizing and variance do.
How many simulations should I run?
1,000 simulations of 500 bets is a good default for stable percentile estimates. More simulations smooth out the tails (the rare best and worst cases) but take slightly longer to compute in the browser.
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Responsible Gambling
Gambling should be entertaining, not a way to make money. Only bet what you can afford to lose, and never chase your losses.
- Betting more than you can afford to lose
- Chasing losses with bigger bets
- Lying to others about gambling habits