Risk of Ruin Calculator: The Complete Survival Guide (2026)

Risk of Ruin (RoR) is the single most important metric in gambling mathematics. It represents the probability that you will lose your entire bankroll before achieving your goals.

While most bettors focus on "how much can I win?", professional bettors focus on "how do I ensure I never lose everything?". This calculator helps you answer that question.

What is Risk of Ruin in Betting?

Risk of Ruin is the mathematical probability that a bettor's bankroll will drop to zero (or a point where they can no longer place bets) given their:

Win Rate (Probability of winning)
Odds (Payout ratio)
Stake Size (Percent of bankroll wagered)

Key Insight: Even with a positive edge (profitable strategy), your Risk of Ruin is never zero if you bet too aggressively. Variance can bankrupt a winning player.

Why "Edge" Isn't Enough

Imagine you have a coin that lands Heads 55% of the time. You have a massive 10% edge.

If you bet 100% of your bankroll on each flip, you will go broke the first time it lands Tails (45% chance).
If you bet 1% of your bankroll, your chance of going broke is mathematically near zero (< 0.01%).

Stake sizing is the primary lever you control to manage risk.

How to Use the Risk of Ruin Calculator

Our tool above simplifies complex probability theory into actionable data. Here's how to interpret the inputs:

1. Win Rate (%)

The percentage of bets you expect to win.

Break-even: 50% (at 2.0 odds) or 52.4% (at 1.91 odds).
Professional: 53-56%.
Unrealistic: >60% (unless arbitrage or match fixing).

2. Average Odds

The decimal odds you typically bet on.

Standard: 1.91 (-110 American) for spreads.
Moneyline: Can vary widely.
Higher odds increase variance and require a larger bankroll.

3. Stake Size (%)

The percentage of your current bankroll you wager on a single bet.

Conservative: 1-2%
Aggressive: 3-5%
Reckless: >5%

4. Target Drawdown

Most calculators only show "Total Ruin" (0$). Our advanced tool lets you calculate the risk of hitting a specific loss limit, like losing 50% of your money.

The Mathematics Behind the Ruin

For those who want to understand the engine under the hood, here are the core formulas.

The Simple Formula (Even Money Bets)

If you only bet on outcomes with 2.0 decimal odds (+100 American):

RoR = \left( \frac{1 - A}{1 + A} \right)^n

Where:

A = Your Edge (Win% - Loss%)
n = Number of units in your bankroll

The General Formula (Any Odds)

For betting at arbitrary odds, there is no closed-form solution. We must solve the following equation for z:

p \cdot z^{1+b} + q - z = 0

Where:

p = Probability of winning
q = Probability of losing
b = Net odds (Decimal odds - 1)
z = A value between 0 and 1

Once z is found (using numerical methods like Newton-Raphson), the Risk of Ruin is:

RoR = z^{\text{Bankroll Units}}

Did you know?

Our calculator runs this advanced algorithm in real-time to give you precise results for any odds, not just 50/50 bets.

3 Ways to Reduce Your Risk of Ruin

If your calculated risk is too high (e.g., >5%), you have three levers to pull:

1. Decrease Your Stake Size (The Kelly Criterion)

This is the most effective method. Halving your bet size doesn't just halve your risk—it reduces it exponentially.

Strategy: Use the Kelly Criterion Calculator to find the mathematically optimal limit, then bet half of that amount ("Half Kelly") for safety.

2. Increase Your Bankroll

Doubling your starting bankroll (while keeping the absolute bet size same) doubles your "life points".

Example: Betting $50 with a$ 1,000 bankroll is risky (5% stake). Betting $50 with a$ 5,000 bankroll is safe (1% stake).

3. Improve Your Win Rate

Finding better Value Bets increases your edge.

A 1% increase in win rate can cut your Risk of Ruin by 90% or more due to the exponential nature of probability.

Risk of Ruin vs Drawdown: What's the Difference?

Metric	Definition	Is it Fatal?
Drawdown	A decline from a previous peak (e.g. -20%).	No. You still have chips to play.
Risk of Ruin	The probability of hitting zero (or a stop-loss).	Yes. Game over.

Professional bettors accept Drawdown as an inevitable part of the job. They fear Ruin and structure their bankroll to make it statistically impossible.

Real-Life Examples (Case Studies)

Scenario A: The "Aggressive" Bonus Hunter

Bankroll: $1,000
Bet: $50 (5%)
Odds: 2.0
Win Rate: 52% (Small edge)
Risk of Ruin: 13.5%
Verdict: Risky. There is a 1-in-7 chance this bettor goes bust despite having an edge.

Scenario B: The "Disciplined" Pro

Bankroll: $10,000
Bet: $100 (1%)
Odds: 1.91 (-110)
Win Rate: 54% (Solid edge)
Risk of Ruin: 0.003%
Verdict: Safe. It would take a catastrophic, historically rare event to bankrupt this player.

Games with lower variance have inherently lower risk of ruin for equivalent bankroll and stake sizes. For example, Joker Poker has variance around 22.5, while Full Pay Deuces Wild has variance of 25.75—despite offering positive expected value (100.76% RTP), it requires larger bankrolls to survive the extreme swings. High-volatility slots (variance 25-50+) make it even harder to avoid ruin without proper bankroll management.

Conclusion

Risk of Ruin is the "check engine light" of sports betting. If it's flashing red (>5%), you are driving too fast.

The Golden Rule: Always size your bets so that your Risk of Ruin is negligible (<1%). This ensures you stay in the game long enough for your mathematical edge to generate profit.

Kelly Calculator – Find your optimal stake.
Bingo Probability – Calculate odds in casino games.
Bankroll Growth – Simulate your future profits.
Odds Converter – Switch between Decimal, Fractional, and American.

Risk of Ruin Calculator: Survival Probability for Bettors (2026)