In sports betting, having a winning strategy is only half the battle. The other half is Bankroll Management. Even a bettor with a proven edge can lose their entire account if they bet too much per game or run into a streak of bad variance.
This concept is known as the Risk of Ruin (RoR). It is the mathematical probability that your bankroll will reach zero before it reaches your profit goals. Use our free calculator below to check if your current staking strategy is safe or reckless.
How to Use the Risk of Ruin Calculator
This tool uses the Kelly Criterion mathematics to determine the likelihood of going bust based on your edge and bankroll size. Here is how to enter your data:
- Win Rate (%): Enter your historical strike rate. For a standard spread bettor (-110 odds), 52.38% is break-even. Anything above 53% is considered a winning edge.
- Avg Decimal Odds: Enter the average odds you bet on.
- Standard Point Spread (-110) = 1.91
- Even Money (+100) = 2.00
- Bankroll (Units): Enter how many “units” you currently have. If you bet $100 per game and have $5,000 in your account, you have 50 Units.
Real-World Examples: Are You Safe?
Risk of Ruin highlights why a large bankroll is necessary to weather the storm of variance. Let’s look at two scenarios for a winning bettor.
Scenario 1: The Aggressive Bettor (High Risk)
You are a winning bettor with a 55% win rate on standard spreads (1.91 odds). However, you play aggressively and only keep 20 bets (units) in your account.
- EV: +5.05% (Great edge!)
- Risk of Ruin: 13.5%
Verdict: Despite being a good handicapper, there is a 1 in 7 chance you will go broke simply due to bad luck.
Scenario 2: The Professional Bettor (Safe)
You have the exact same stats (55% win rate at 1.91 odds), but you practice strict bankroll management and keep 100 bets (units) in reserve.
- EV: +5.05%
- Risk of Ruin: < 0.01%
Verdict: By having a deeper bankroll, your risk of going bust drops to near zero. You have mathematically “solved” survival.
Frequently Asked Questions (FAQ)
What is an acceptable Risk of Ruin percentage?
Professional bettors typically aim for a Risk of Ruin below 1% (and ideally below 0.1%). If your RoR is above 5%, your staking sizing is likely too large for your edge, and you are taking an unnecessary gamble with your funds.
How can I lower my Risk of Ruin?
There are three ways to lower your risk:
1. Increase your Bankroll: Add more funds or reduce your bet size (e.g., bet $50 instead of $100).
2. Increase your Win Rate: Become a better handicapper.
3. Get Better Odds: Shop for lines to improve your payout without changing your win probability.
What if the calculator shows 100% Risk?
If the calculator shows 100%, it means your Expected Value (EV) is negative or zero. Mathematically, if you play a negative-EV game forever (like Roulette or Slots) without an edge, the probability of eventually losing your money is 100%, regardless of your bankroll size.
Does this apply to Flat Betting or Kelly Betting?
This calculator assumes you are re-staking your bankroll or betting a fixed percentage (proportional betting), which aligns with Kelly Criterion logic. If you are flat betting (betting the same dollar amount forever), the math is slightly different, but the general principle remains: a larger bankroll drastically reduces the chance of ruin.