Risk of Ruin Calculator
Estimate probability of account ruin from win rate, reward/risk profile, and fixed risk per trade. Essential for position sizing and bankroll management.
Model uses simplified fixed-risk assumptions. Real trading outcomes vary due to slippage, regime changes, and non-independent outcomes.
How to use Risk of Ruin Calculator
The Risk of Ruin Calculator computes the probability of losing your entire trading capital (or a defined percentage of it) given your win rate, average win/loss size, and risk per trade. This is the ultimate survivability metric: even a positive-expectancy strategy can go bust if individual trade risk is too high and an unlucky streak occurs.
For example, risking 10% per trade with a 55% win rate and 1.5:1 reward-to-risk has a surprisingly high ruin probability. Reducing risk to 2% per trade drops ruin probability to near zero while only moderately reducing long-term growth. This calculator makes the tradeoff between aggression and survival explicit and quantifiable.
Input guide and assumptions
Win rate and payoff ratio define your strategy's expected value. Risk per trade is the percentage of capital risked on each position. Ruin threshold is the drawdown percentage at which you consider yourself "ruined" — typically 50-100% of capital.
Starting capital and number of trades matter for simulation accuracy. With more trades, the law of large numbers works in your favor if expected value is positive, but short-term streaks can still cause ruin if risk per trade is excessive. The calculator runs a Monte Carlo simulation to estimate ruin probability across thousands of possible trade sequences.
How to interpret results correctly
Risk of ruin quantifies the probability that your trading account will hit a terminal drawdown — typically 50% or 100% loss — given your current win rate, average win/loss ratio, and percentage risked per trade. A result above 5% is a red flag: it means there is a meaningful statistical chance your account will be destroyed even if your strategy has positive expectancy. Compare your result against the <a href="/kelly-calculator/">Kelly criterion calculator</a> to see whether your position sizing aligns with theoretically optimal risk allocation.
The output is most useful as a relative comparison tool. If your risk of ruin at 2% risk per trade is 0.8% but jumps to 14% at 5% risk, that quantifies exactly how dangerous the larger bet size is. Run the calculator with your actual last-100-trade statistics — not hypothetical numbers — for the most accurate reading. Pair this with our <a href="/drawdown-calculator/">drawdown calculator</a> to see the probable maximum drawdown depth and recovery time associated with your current risk parameters.
Practical scenarios and planning workflow
A swing trader with a 52% win rate and 1.8:1 reward-to-risk ratio enters the calculator with 2% risk per trade. The ruin probability is 0.3% — well within safe territory. They test 4% per trade and ruin jumps to 9.7%, confirming they should stay at 2%. A scalper with 68% win rate but only 0.9:1 R:R finds their ruin at 1% risk is 2.1% — the high win rate partially compensates for the poor ratio, but a losing streak of 8 trades would still be devastating.
A crypto futures trader backtests 200 trades: 45% win rate, 2.5:1 average R:R. At 1.5% risk per trade the ruin probability is 0.1% — very safe. They consider increasing to 3% risk to accelerate growth. The calculator shows ruin rises to 4.2%. They use the <a href="/position-size-calculator/">position size calculator</a> to calibrate an intermediate 2.2% risk level that keeps ruin below 1% while improving capital efficiency.
Risk and execution checklist
- Before running the calculation: 1) Calculate your actual win rate from at least 50 trades — fewer produces unreliable statistics. 2) Compute your average winning trade divided by average losing trade to get the R:R ratio. 3) Decide what constitutes 'ruin' for your account — 50% drawdown is a common threshold because recovering from it requires a 100% gain.
- After receiving the result: verify that your risk-per-trade input matches what you actually risk (including slippage and fees, not just stop-loss distance). If ruin exceeds 1%, reduce risk per trade or improve your R:R ratio before continuing to trade live. Document the result in your trading journal alongside your current strategy parameters.
Common mistakes to avoid
- The most dangerous mistake is using hypothetical or optimistic win rates instead of actual trading data. A trader who 'feels' they win 60% of trades but actually wins 48% will dramatically underestimate their ruin probability. Always pull real numbers from your trade history — at minimum the last 50 trades, ideally 100+. Small sample sizes produce confidence intervals so wide that the ruin estimate is essentially meaningless.
- Another critical error is ignoring the compounding effect of consecutive losses. Even with 2% risk per trade, a losing streak of 10 trades — which occurs once every 1,024 trades at 50% win rate — costs 18.3% of your account (not 20%, due to compounding). Traders who mentally model risk as linear drastically underestimate how quickly drawdowns deepen. Use the calculator output to stress-test scenarios with 15–20 consecutive losses.
Performance benchmarks and expectation ranges
Professional crypto traders target a risk of ruin below 1% with typical parameters: 50–60% win rate, 1.5:1 to 3:1 R:R ratio, and 1–2% risk per trade. At 55% win rate with 2:1 R:R and 1% risk, ruin probability drops to approximately 0.05% — near-zero for practical purposes. Most prop trading firms require ruin under 0.5% before allowing live capital allocation, and many set the threshold at 0.1%.
Dangerous territory starts above 5% ruin probability. At 50% win rate, 1:1 R:R (breakeven expectancy), even 1% risk per trade produces roughly 50% ruin probability because the strategy has no edge. This demonstrates that ruin is heavily sensitive to edge quality — a small improvement from 1:1 to 1.3:1 R:R with the same win rate can cut ruin from 50% to under 5%. Always test how marginal improvements in either win rate or R:R affect the output.
Execution templates you can reuse
Step-by-step workflow: open your trading journal → calculate exact win rate and average R:R from last 100 trades → enter these into the risk of ruin calculator → test your current risk percentage → if ruin exceeds 1%, reduce risk per trade by 0.5% increments until it drops below 1%. Record the safe risk percentage and enforce it as a hard rule in your <a href="/position-size-calculator/">position size calculator</a> for every future trade.
Advanced execution: run the calculator quarterly as your trading statistics evolve. If your win rate improves from 52% to 57% over a quarter, you may safely increase risk per trade from 1.5% to 2%. Conversely, during drawdown periods when your trailing win rate drops, temporarily reduce position sizes. This dynamic adjustment keeps ruin probability consistently below 1% regardless of performance cycles.
Data hygiene and model maintenance
Recalculate your risk of ruin at least monthly, or whenever your trading statistics change by more than 3 percentage points. A win rate that drops from 55% to 50% can increase ruin probability by 10x or more depending on your R:R ratio. Keep a simple spreadsheet tracking monthly win rate, R:R, risk per trade, and resulting ruin probability to spot dangerous trends early.
Maintain separate ruin calculations for each strategy or market you trade. A BTC scalping strategy with 70% win rate and 0.8:1 R:R has a completely different risk profile than an altcoin swing strategy with 40% win rate and 4:1 R:R. Combining them into one calculation masks the true risk of each. If any single strategy exceeds 2% ruin, address it independently before it contaminates your overall account.
Final validation before capital deployment
Validate your ruin calculation by running a Monte Carlo simulation with the same parameters. Many free tools generate 10,000 random trade sequences from your win rate and R:R — the percentage of sequences that hit your ruin threshold should closely match the calculator's analytical output. If they diverge by more than 2 percentage points, double-check your input parameters.
Cross-validate against your actual maximum drawdown history. If the calculator says ruin is 0.2% but you have already experienced a 40% drawdown in 6 months of trading, your inputs may be too optimistic. Re-examine whether your reported win rate and R:R include all trades — particularly partial exits, gap losses, and trades closed at worse-than-stop prices due to slippage.
Frequently asked questions
What is risk of ruin in crypto trading?
Risk of ruin is the probability that your trading account will lose a specified percentage of capital (e.g., 50% or 100%) given your win rate, reward-to-risk ratio, and the percentage risked per trade. Even profitable strategies can lead to ruin if position sizes are too large.
What risk per trade keeps the risk of ruin near zero?
Risking 1-2% of your account per trade keeps the risk of ruin extremely low for most strategies with a positive edge. At 1% risk per trade, even a strategy with a 40% win rate and 2:1 reward-to-risk ratio has a negligible probability of hitting a 50% drawdown.
How does win rate affect the risk of ruin?
A higher win rate dramatically reduces the risk of ruin, but only when paired with appropriate position sizing. A 60% win rate with 5% risk per trade can still have a meaningful ruin probability, while a 45% win rate with 1% risk per trade and a 3:1 reward-to-risk may have virtually zero ruin risk.
What is the difference between risk of ruin and maximum drawdown?
Maximum drawdown is the largest peak-to-trough decline you have experienced historically. Risk of ruin is a forward-looking probability that estimates how likely you are to hit a catastrophic loss level. You can have small historical drawdowns but still face meaningful ruin risk if position sizes are too large.
Can I have a positive expectancy but still go bankrupt?
Yes. A positive expected value per trade does not prevent ruin if your position sizing is too aggressive. The classic example is a coin flip paying 2:1 — positive expectancy, but betting 100% each time guarantees eventual ruin. The Kelly Criterion helps find the position size that avoids this trap.
How many trades does the risk of ruin calculation assume?
The standard risk of ruin formula assumes an infinite series of trades, giving you the probability of ever hitting the ruin threshold regardless of how many trades you take. For a fixed number of trades, the actual ruin probability is lower, but using the infinite-horizon formula provides a conservative safety margin.