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Risk of Ruin Calculator
Calculate the probability your bankroll goes to zero based on your edge, bet size, and starting capital. The math runs entirely in your browser.
Your Inputs
≈ $100 per bet · 50 units in bankroll
Decimal: 1.909
Results
Ruin is more likely than survival. Reduce stake size.
What this means
Out of every 100 hypothetical bettors with your exact inputs, approximately 31 would go broke before their edge plays out. Lower stake size is the fastest way to drop this number.
Ruin by Stake Size
The dashed horizontal line marks the 5% threshold most professional bettors stay below. The vertical line marks your current stake.
Run this on your real bets
Stop estimating your edge.
This calculator uses inputs you guess at. TrueLine pulls your actual win rate and average odds from your tracked bet history, then runs a 2,000-simulation Monte Carlo to show your real risk of ruin — updated automatically as your numbers change.
How the math works
This calculator uses the classical fixed-unit-size risk of ruin formula:
RoR = ((1 - edge) / (1 + edge)) ^ units
Where edge is your expected value per bet (computed from your win rate and average odds), and units is your bankroll divided by your bet size.
The formula assumes fixed unit sizing (always betting the same dollar amount), independent outcomes, and a constant edge. Real betting violates all three assumptions to some degree, which is why a Monte Carlo simulation against your actual bet history produces more accurate results than the formula alone.
All math runs in your browser. We don't log or store your inputs.
Frequently asked questions
What is risk of ruin in sports betting?
Risk of ruin is the probability that your bankroll falls to zero given your win rate, edge, bet size, and starting capital. It's the most important metric in bankroll management — most professional bettors target risk of ruin under 1-2%.
How is risk of ruin calculated?
For fixed unit-size betting at standard odds, risk of ruin = ((1 - edge) / (1 + edge)) ^ units, where edge is your expected value per bet as a decimal and units is how many betting units fit in your bankroll. Smaller bet sizes exponentially lower your risk of ruin.
What is an acceptable risk of ruin?
Most professional bettors target under 1% risk of ruin. Below 5% is conservative and defensible. Above 15% is considered reckless. Above 30% means ruin is more likely than survival, regardless of your edge.
Is this calculator free?
Yes, completely free. No signup, no rate limit, no gating. The math runs entirely in your browser — we don't store any of your inputs.