The formula
profit factor = gross profit ÷ gross loss
Both totals are absolute: every winning trade added together, every losing trade added together as a positive number. A record of $8,400 won against $6,000 lost gives 1.40 — meaning $1.40 came back for every $1.00 that went out.
Anything above 1 is profitable. Below 1 is not. The ratio does not depend on account size, position size or the number of trades, which is what makes it comparable across records that otherwise share nothing.
What counts as good
Rough bands, and they are conventions rather than laws:
| Profit factor | Reading |
|---|---|
| Below 1.0 | Loses money |
| 1.0 – 1.2 | Marginal; costs and slippage can erase it |
| 1.3 – 1.6 | A workable edge for most discretionary trading |
| 1.7 – 2.5 | Strong, and worth checking for overfitting if backtested |
| Above 3.0 | Usually a short sample, an outlier, or a curve fit |
The last row deserves the suspicion. Very high profit factors are common in backtests and rare in live records, because the things that produce them — a handful of enormous winners, or a period that suited the strategy — do not repeat on demand.
The blindness that matters
Profit factor knows the totals and nothing about their shape. Two records can share the same 1.40 and be entirely different businesses:
- One earns it across two hundred trades, no single winner larger than 3% of gross profit.
- The other earns it across the same two hundred trades, with one winner supplying half the gross profit.
Remove one trade from the second record and it is a losing strategy. Remove any trade from the first and nothing changes. The ratio cannot see the difference, and this is precisely why strategy reports and signal sellers quote it in preference to anything else.
The check takes one division: largest winner divided by gross profit. Above roughly 20%, the ratio is describing a trade rather than a method.
Reading it with the other two
Profit factor, win rate and expectancy answer three different questions, and only together do they describe a record.
Profit factor says whether the totals are favourable. Win rate says how often you are right. Expectancy says what one trade is worth — and, with a sample size, how uncertain that is. A high profit factor with a low win rate is a trend-following shape; the same ratio with a high win rate is a mean-reversion shape. The number is the same; the drawdowns you will live through are not.