Drawdown Calculator vs Risk of Ruin
Assessing Current Damage vs Preventing Future Blowups
Drawdown and Risk of Ruin both deal with losing money, but they look at the problem from opposite directions. Drawdown measures what has already happened — how far your account has fallen from its peak. Risk of Ruin estimates what could happen — the probability of losing your entire account.
Together, they give you a complete picture of risk: where you are now and where your strategy could take you. This guide explains when each metric matters most.
Quick Answer: Which Should You Use?
Use Drawdown Calculator if:
- •You want to measure your current or historical loss from peak
- •You need to know how much recovery is required
- •You're evaluating past performance or a losing streak
Use Risk of Ruin if:
- •You want to estimate the probability of blowing up your account
- •You're deciding how much to risk per trade going forward
- •You need to stress-test a strategy before deploying capital
Drawdown tells you the damage. Risk of Ruin tells you the odds of total failure. Use drawdown to react; use Risk of Ruin to plan.
What Is Drawdown?
Drawdown measures the percentage decline from an account's peak value to its subsequent low. A 20% drawdown means your account dropped from its high point by one-fifth. The recovery needed is always larger — a 20% loss requires a 25% gain to get back to even.
Drawdown is backward-looking. It tells you what already happened, not what will happen next.
Why Traders Track It
- •Quantifies the severity of a losing period
- •Shows the recovery % needed to return to peak
- •Helps trigger strategy reviews at defined thresholds
Where It Falls Short
- •Only looks backward — no predictive power
- •Doesn't tell you the probability of deeper losses
- •Can't help you decide position size going forward
What Is Risk of Ruin?
Risk of Ruin estimates the probability that your account balance will hit zero (or a defined threshold) given your win rate, risk per trade, and payoff ratio. It's a forward-looking survival metric.
Even profitable strategies can blow up if position sizing is too aggressive. Risk of Ruin quantifies that danger before it happens.
Why Traders Use It
- •Stress-tests a strategy before you risk real money
- •Shows whether your risk per trade is sustainable
- •Helps set maximum risk limits for a trading system
Tradeoffs
- •Requires reliable win rate and payoff data
- •Assumes consistent risk per trade (which may not hold)
- •Doesn't capture correlation or market regime changes
Drawdown vs Risk of Ruin — Side-by-Side
| Feature | Drawdown | Risk of Ruin |
|---|---|---|
| Measures | Peak-to-trough loss | Probability of blowup |
| Timeframe | Historical / current | Forward-looking |
| Input | Account values | Win rate + risk per trade |
| Output | % decline + recovery needed | Probability 0-100% |
| Best for | Assessing current damage | Preventing future blowups |
| Action | Adjust strategy | Adjust position size |
| Perspective | Backward-looking | Forward-looking |
Common Trading Scenarios
After a Losing Streak
Use drawdown to measure the damage and calculate how much you need to gain to recover. A 30% drawdown requires a 43% return just to break even.
Before Going Live With a New Strategy
Run Risk of Ruin with your backtest stats. If the ruin probability is above 5%, reduce your risk per trade before deploying real capital.
Setting a Maximum Drawdown Rule
Use both together: set a drawdown threshold (e.g., 20%) as your circuit breaker, and use Risk of Ruin to ensure your sizing keeps the probability of hitting that threshold low.
Try the Calculators
Measure your current drawdown, then check your probability of ruin going forward.
Related comparisons
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Options Probability estimates a trade's chance of profit; Risk of Ruin estimates long-run blow-up risk. Use the right one for the decision.
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Learn when to use Kelly Criterion vs Risk of Ruin, how bet sizing affects survival risk, and which metric matters for your trading system.
Learn how implied volatility and Black-Scholes differ, how IV feeds theoretical pricing, and when each matters for options decisions.
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Risk/reward evaluates a single trade setup. Kelly Criterion sizes your bet based on your edge. Learn when to use each for better trading decisions.
Options P/L shows your exact profit at expiration. Expected Move shows the probable price range. Use both to plan options trades with context.
Position Size calculates shares for stock trades. Lot Size calculates units for forex trades. Same concept, different markets and conventions.
Related Strategy Guides
Key Takeaway
- •Drawdown measures how much you've lost from your peak — it's your damage report
- •Risk of Ruin estimates the probability of total account loss — it's your survival forecast
Drawdown reacts to the past. Risk of Ruin protects the future. Every serious trader should monitor both — one to know where they stand, the other to know if they'll survive.
Frequently Asked Questions
What is a normal drawdown for active traders?
Most professional traders aim to keep max drawdown under 20%. Beyond 30%, recovery becomes psychologically and mathematically difficult.
What Risk of Ruin percentage is acceptable?
Most traders target under 1-5%. If your Risk of Ruin is above 10%, your position sizing is likely too aggressive for your win rate.
Can a profitable strategy still have high Risk of Ruin?
Yes. A strategy with a 55% win rate can still blow up if you risk 10% per trade. Risk of Ruin depends on sizing, not just edge.
Should I stop trading after a large drawdown?
Not necessarily, but you should reassess. Check your Risk of Ruin at current sizing — if it's elevated, reduce position size before continuing.