Understanding Max Drawdown: The Number That Keeps You Alive

2026-07-07

Beginners obsess over returns. Survivors obsess over drawdown. Return tells you how much a strategy makes; max drawdown tells you whether you will still be in the game to collect it. It is the single most important risk number on any backtest, and the one most likely to end your account if you ignore it.

What max drawdown is

Max drawdown (MDD) is the largest peak-to-trough drop in your equity, measured as a percentage. If your account climbs to $12,000 and then falls to $8,000 before recovering, that is a 33% drawdown — you lost a third of your capital at the worst point. MDD captures the deepest such valley over the whole test.

Why recovery is asymmetric

Losses hurt more than equal-sized gains help, because they compound against you. A −50% drawdown needs a +100% gain just to break even. −80% needs +400%. This asymmetry is why deep drawdowns are so dangerous: the hole gets exponentially harder to climb out of the deeper it goes.

A blunt rule of thumb: could you keep trading the plan, calmly, through its worst historical drawdown? If a 40% drop would make you quit, override the system, or run out of margin, then a strategy with a 40% MDD is not tradable for you — no matter how good its return looks.

Drawdown sets your leverage

Leverage multiplies drawdown just as it multiplies returns. A strategy with a 30% max drawdown at 1x becomes a liquidation candidate at 3x (roughly 90% down). This is the calculation that actually keeps you alive: size leverage from the worst drawdown, not from the average return. Return is the reward; drawdown is the constraint.

The future is always worse

Here is the uncomfortable part: your backtest's max drawdown is a floor, not a ceiling. It is the worst thing that happened in your sample — the future routinely finds a deeper one. A strategy that showed 25% over seven years can easily print 35% next year on a regime it never saw. Leave a wide margin below whatever the backtest shows.

How to read it on this site

The results panel shows overall MDD and drawdown for each period window.
Compare MDD to return — a high return with a huge drawdown is fragile, not impressive.
Prefer smoother equity curves; the shape of the path matters as much as the endpoint.

Never choose leverage from returns alone. Find your strategy's worst historical drawdown, assume the real one will be worse, and size so you can survive it without being liquidated or breaking discipline. Survival first; returns follow.