Profit Factor Explained

Profit factor answers a single question about a set of closed trades: how many dollars did the winners make for every dollar the losers gave back? It is built from two totals. Gross profit is the sum of all winning trades; gross loss is the sum of all losing trades, taken as a positive number.

Because both totals are in account currency, the ratio is unitless: a profit factor of 1.50 reads as “$1.50 made per $1 lost”, whatever the account size. That makes it comparable across accounts — and easy to compute from any trade history.

The arithmetic gives the value its meaning directly. At exactly 1.0 the winners and losers cancel out — the closed trades broke even before anything else is considered. Above 1.0, gross profit exceeded gross loss; below 1.0, the losing trades took back more than the winners made. A useful identity: net profit equals gross loss × (profit factor − 1). A profit factor of 1.25 with $4,000 of gross loss is $1,000 of net profit; 0.85 with the same gross loss is a $600 net loss.

What counts as a workable value depends on context rather than a universal threshold. The same strategy shows different profit factors across market periods; spreads, commission and swap pull the number down to the extent they are booked into trade results; and a value computed from 30 trades carries far less information than the same value computed from 500. Comparing a strategy’s profit factor against its own history is usually more telling than comparing it against a quoted benchmark.

Note how small the sample is. Swap the $100 winner for a $300 winner and the profit factor jumps from 1.50 to 2.00 — a one-trade change that says nothing about how the strategy behaves over hundreds of trades.

Profit factor combines two more basic statistics: how often a strategy wins, and how large its average win is relative to its average loss (the payoff ratio). Expressed that way:

Many combinations solve that equation, so very different styles can land on the same value. The two 50-trade samples below both show a profit factor of 1.80 with identical gross totals — but they would feel nothing alike to trade:

The ratio collapses every property of a track record except one — the balance between total wins and total losses. Several things it cannot see:

• Order of trades. The same trades in a different sequence produce the same profit factor but a completely different drawdown path.
• Drawdown. A 1.6 profit factor is consistent with a 5% maximum drawdown or a 40% one — the ratio carries no information about either.
• Outliers and sample size. One large win inflates the number; with few trades, the value is mostly noise.
• Open positions. Only closed trades enter the calculation, so floating profit or loss is invisible to it.

None of these are flaws in the formula — they are reminders that one ratio cannot summarise a distribution. The same caution applies even more strongly to simulated results, as covered in the guide to misleading backtests.

MT4 and MT5 print gross profit, gross loss and profit factor in the summary block of both account history reports and Strategy Tester reports, calculated from closed trades in the deposit currency. In the MQL5 tester statistics the value is the constant STAT_PROFIT_FACTOR — the gross profit statistic divided by the gross loss statistic.

One edge case is worth knowing: when a test produces no losing trades at all, gross loss is zero and the platform reports the profit factor as the largest representable number — effectively infinite. A short test showing a profit factor in the thousands is describing an empty denominator, not an edge. To see how the ratio interacts with the other report statistics on your own results, the free MetaTrader Backtest Analyzer breaks a tester report down metric by metric.

Profit factor works best as one leg of a three-legged read. Expectancy converts the same history into an average result per trade in money, which profit factor deliberately ignores — a 1.8 ratio could be $4 per trade or $400. Maximum drawdown describes the path: how deep the losing stretches cut while that ratio was being earned.

A practical review of a live account or an EA therefore reads the three together per strategy and per symbol: profit factor for the win/loss balance, expectancy for the per-trade magnitude, drawdown for the cost of holding on. How expectancy is calculated — and why it pairs naturally with profit factor — is covered in the expectancy guide, and you can run your own numbers through the Trading Expectancy Calculator.