Max Drawdown Explained: How Much Can You Afford to Lose?

Max Drawdown Is the Worst Losing Streak Your Equity Curve Has Ever Seen

Max drawdown is the largest percentage decline from a peak in portfolio value to the lowest point (trough) reached before a new peak is set. If a $100,000 account rises to $130,000, then falls to $91,000 before recovering, the max drawdown is 30% — calculated from the $130,000 peak, not the original $100,000 starting balance.

It's one of the few metrics that answers the question every trader eventually asks the hard way: how bad can it actually get?

How to Calculate Max Drawdown

The formula is straightforward:

Drawdown = (Trough Value − Peak Value) / Peak Value

Max drawdown is the largest such drawdown across the entire equity curve, not just the most recent one. To calculate it properly:

1. Track the running peak (highest equity value reached so far) at every point in time
2. At each point, compute the percentage decline from that running peak
3. Take the single largest decline across the whole history

A strategy can have many small drawdowns and one catastrophic one — max drawdown only reports the worst.

Why Max Drawdown Matters More Than Average Return

Two strategies can post identical average annual returns and be completely different in risk:

Strategy	Avg Annual Return	Max Drawdown	Recovery Needed
A	15%	12%	13.6% gain
B	15%	55%	122% gain

This is the part most beginners underestimate: losses and the gains needed to recover from them are not symmetric. A 20% drawdown requires a 25% gain to break even. A 50% drawdown requires a 100% gain. A 70% drawdown requires a 233% gain. The deeper the hole, the more disproportionately hard it is to climb out — which is why a strategy with a large max drawdown can be mathematically ruinous even if its long-run average return looks attractive on paper.

The Recovery Math

Drawdown	Gain Required to Recover
10%	11.1%
20%	25%
30%	42.9%
40%	66.7%
50%	100%
70%	233%
90%	900%

This table is why professional risk managers care about drawdown more than raw return — and why "it averaged 20% a year" is an incomplete picture of any strategy without also knowing its worst peak-to-trough decline.

Max Drawdown vs Volatility

Volatility (often measured as standard deviation of returns) describes how much a portfolio's value fluctuates in general. Max drawdown describes the single worst sustained decline. A strategy can have low day-to-day volatility but still experience a large, slow-grinding drawdown over months — volatility metrics can miss this because they average out both up and down moves, while drawdown only cares about the depth of the worst decline.

Both are useful, but they answer different questions:

• Volatility: how bumpy is the ride, on average?
• Max drawdown: what's the worst single fall you'd have had to sit through?

What Counts as an Acceptable Max Drawdown?

There's no universal answer, but there are useful reference points:

• Diversified long-term equity portfolios: drawdowns of 20-35% have occurred even in broad index funds during real bear markets (2008, 2020, 2022), so treat this as a realistic floor for what "normal" looks like over a multi-decade horizon
• Actively managed or leveraged strategies: many professional systematic funds target max drawdowns under 15-20%, because larger drawdowns tend to trigger investor redemptions regardless of the strategy's long-term edge
• Individual discretionary traders: a max drawdown beyond 20-25% of account equity is where most traders start making emotionally driven decisions rather than following their process, which is often more damaging than the drawdown itself

The right threshold ultimately depends on your time horizon, how the capital is funded (your own savings vs. other people's money), and your ability to psychologically tolerate the drawdown without abandoning the strategy at the worst possible time.

Using Max Drawdown to Size Positions

Because drawdown compounds so unfavorably, max drawdown should directly inform position sizing:

• If a strategy has historically drawn down 30% at full size, consider what drawdown you can genuinely tolerate before deviating from the plan, and scale position size down proportionally if that's larger than your comfort threshold
• Backtested max drawdown is a floor, not a ceiling — live markets can and do produce drawdowns worse than anything in the historical sample, especially in strategies with a limited backtest window (see How Many Trades Do You Need for a Statistically Valid Backtest? for why short histories understate tail risk)
• Combine drawdown analysis with position sizing rules so that no single losing streak can force you out of the market entirely

Max Drawdown Is Backward-Looking

A critical limitation: max drawdown is calculated from historical data, so it only tells you the worst decline that has happened, not the worst that could happen. A strategy with a 10-year backtest showing a 15% max drawdown has simply not yet lived through a scenario like 2008 or a flash crash within that sample. Treat historical max drawdown as a minimum estimate of tail risk, not a guarantee of a ceiling.

Summary

Concept	Takeaway
Max drawdown	Largest peak-to-trough decline in equity
Why it matters	Losses require disproportionately larger gains to recover
Volatility vs drawdown	Volatility is average bumpiness; drawdown is worst-case depth
Backtested drawdown	A floor, not a guaranteed ceiling
Practical use	Size positions so the worst realistic drawdown stays inside your risk tolerance

Max drawdown is the metric that keeps average-return numbers honest. Before trusting any strategy's headline performance, ask what its worst peak-to-trough decline was — and whether you could have actually sat through it without pulling the plug.

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Related reading:

• Position Sizing: How to Calculate How Much to Risk Per Trade — turning drawdown tolerance into concrete position sizes
• Risk-Reward Ratio Explained — structuring individual trades around acceptable loss
• How Many Trades Do You Need for a Statistically Valid Backtest? — why short backtests understate real drawdown risk
• Portfolio Diversification: How Many Stocks Is Enough? — reducing drawdown through diversification