Most traders look at return figures first. Professional risk managers look at drawdown first. This guide explains why — and what to do with the numbers once you understand them.
What is drawdown?
Drawdown is the peak-to-trough decline in account equity before a new high is reached. If your account grows from $10,000 to $12,000 and then drops to $10,200 before recovering to $12,500, the drawdown was $1,800 (= 15% from the $12,000 peak). The recovery came when equity exceeded $12,000 again.
Maximum drawdown is the largest such peak-to-trough decline over the entire backtest period. An EA with -8% max drawdown lost at most 8% from its highest equity point at any moment during the backtest.
Why drawdown matters more than return
A 25% annual return sounds excellent. But if the drawdown to generate it was -40%, you would need to endure watching $10,000 become $6,000 before recovery. Most traders cannot do this psychologically — they stop the EA at the bottom of the drawdown, locking in the loss and missing the recovery.
The ratio CAGR / max drawdown is a useful quality-of-edge metric. Compare:
- EA A: 25% CAGR, -40% max drawdown → ratio 0.6
- EA B: 18% CAGR, -8% max drawdown → ratio 2.25
EA B produces better risk-adjusted compounding over time even at lower headline return.
Worst streak vs max drawdown
Max drawdown is a dollar (or percent) figure. Worst streak is consecutive losses — a different and often more psychologically useful metric. An EA with -8% max drawdown but a worst streak of 8 consecutive losses forces you to sit through 8 losses in a row and trust the system. This is harder than it sounds.
Before deploying an EA, answer: “Can I psychologically accept the worst streak shown in the backtest?” If the answer is no, reduce lot size until the streak’s dollar impact is tolerable.
Recovery time
Recovery time measures how long the EA took to return to a new equity high after the worst drawdown period. EAs with 20-30 day recovery times give you a clear expectation: if you start a live account and immediately hit a bad run, you are likely within 4-6 weeks of recovery. EAs with 90-120 day recovery times test patience and capital reserves for a full quarter.
How to size positions for drawdown survival
A practical rule: size lots so that the EA’s max drawdown translates to no more than 20-25% of your account in dollar terms.
Example: EA max drawdown = -10%. You allocate $5,000. At 0.01 lot on USD pairs, 10% of $5,000 = $500 risk. If the EA’s backtest produced the -10% max drawdown on a 0.01 lot / $5,000 balance, you are correctly sized.
If you are nervous about the drawdown number, halve the lot size. You halve the return, but you also halve the dollar drawdown — and you are far more likely to keep the EA running through a losing streak at a tolerable position size.
The forward-test caveat
Backtested drawdown figures are minimum estimates, not maximum bounds. Live trading produces new market conditions the backtest did not include. Budget for live drawdown of 1.5–2x the backtested max drawdown when sizing your capital allocation.