Grid vs Martingale EA: The Math Behind the Blow-Up

Short answer: a martingale EA doubles its lot after each loss; a grid EA opens more positions as price moves against it and closes them together at a profit. Both win most of the time, which is why their equity curves look so smooth, and both carry a rare loss large enough to erase everything they made. The question is never whether the bad streak comes but when.

What is a martingale EA?

After a losing trade, the next trade's lot is multiplied — usually by 2 — so one win recovers every previous loss plus the original profit. Starting at 0.01 lots:

Losses in a row	Next lot	Total lots traded so far
0	0.01	0.01
3	0.08	0.15
5	0.32	0.63
7	1.28	2.55
10	10.24	20.47

The eleventh trade is a thousand times the first. Long before that, the account runs out of margin or the broker's maximum lot stops the sequence — and the loss is locked in.

How likely is a long losing streak?

More likely than it feels. With a 50% chance of each trade losing, the probability of at least one run of 10 losses in a row is:

Trades taken	Chance of a 10-loss streak
500	about 22%
1,000	about 39%
2,000	about 62%
5,000	about 91%

A martingale EA taking a few trades a day reaches 2,000 trades in a couple of years. Even at a 60% win rate, the chance of an 8-loss streak somewhere in 2,000 trades is roughly 55%.

What is a grid EA?

A grid EA places trades at fixed intervals — say a new buy every 20 pips lower — and closes the whole basket when it reaches a combined profit. It needs no prediction, only for price to come back.

Ten 0.01-lot EURUSD buys spaced 20 pips apart, with price 200 pips below the first, hold a floating loss of about 1,100 pips × $0.10 = $110. That is manageable. The trouble is that most commercial grids also increase the lot at each level — a grid with a martingale inside it — and that trending markets do not come back on schedule.

Why the backtest looks perfect

Both strategies close most trades in profit, so the balance line rises almost without interruption. The damage lives in equity — the open losses the EA is carrying. In the MT5 report:

• A balance drawdown of 3% beside an equity drawdown of 60% is the signature of a strategy holding losers open.
• A very high win rate with an average loss many times the average win.
• A test period that happens to contain no long trend against the grid.

Always read equity drawdown, never balance alone. Our backtesting guide shows where it is.

If you still want to trade a grid or martingale

Some traders do, knowingly. If you are one of them, build the limits in:

1. A hard cap on levels — no more than N positions or N doublings.
2. A maximum total exposure in lots, checked before each new order.
3. An equity stop that closes everything at a fixed percentage loss and stops the EA. The prop-firm guards are the same pattern.
4. Never on a prop-firm challenge. Daily loss limits are exactly what these strategies hit.
5. Size the start lot from the worst case, not the average one.

TradeSmithy includes grid and martingale templates because traders ask how they work. Open one, read the graph, and backtest it over a period with a strong trend before you believe anything its equity curve tells you.

Build a strategy you can explain

The alternative to recovering losses is having fewer of them: a defined stop on every trade and a position size based on account balance. Start free on TradeSmithy to build and export one, and see Pro to backtest it on our servers with the equity curve in full. Why we never quote win rates: what we do not claim.

Frequently asked questions

Is grid trading profitable?

It can be for long stretches, then lose heavily in a sustained trend. Profitability depends on surviving the worst move, not the average one.

What is the difference between grid and martingale?

Martingale increases the lot after losses; a grid adds positions at price intervals. Many EAs combine both, which compounds the risk.

Why do martingale EAs have such high win rates?

Because one win recovers many losses, most sequences end in profit. The rare sequence that does not can erase all of them.

Can a martingale EA pass a prop firm challenge?

It can, briefly — then a single bad day breaches the daily loss limit. Most firms' rules make these strategies a poor fit.