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A trader can win nine trades out of ten and still end up ruined. It sounds impossible until you do the math: nine small wins of 20 euros each bring 180, and the single loss of 250 wipes them out and then some. The account is red despite a 90% win rate, because winning often is not the same as winning efficiently. The metric that catches this, the one that ignores how often you win and asks only whether your profit euros beat your loss euros, is the profit factor.
In short: profit factor is gross profit divided by gross loss and tells you whether the strategy is efficient (a value of 2.0 means 2 euros of profit for every euro lost). Expectancy is the average profit per trade and tells you how much it returns. Profit factor judges efficiency, expectancy judges return, and neither needs a high win rate to be good. A value above 4 on a small sample is more an overfitting warning than a trophy.
The formula is as blunt as it is useful: profit factor = gross profit divided by gross loss. Add up every euro made on winning trades, add up every euro lost on losing trades, and divide the first by the second.
Profit factor = gross profit ÷ gross loss How many euros come in for every euro that goes out
The result tells you how many euros come in for every euro that goes out. A profit factor of 2.0 means the strategy generates two euros of profit for every euro of loss; a profit factor of 1.0 means it breaks even exactly; anything below 1.0 means the losses are winning.
What makes it valuable is exactly what it ignores. It does not care how many trades you won, only about the totals. That is why it exposes the 90% win rate trap from the opening: a glittering win rate with a profit factor below 1.0 is a losing strategy in disguise. Profit factor strips off the disguise and reports the only thing the account ultimately feels, the balance between money in and money out.
The values below are the consensus among professional traders and system developers. They are guidelines, not laws, and they assume a meaningful sample of trades rather than a lucky handful.

The realistic target sits in the green: between 1.5 and 2.5 on a large sample.
Numbers make the idea concrete. Picture a month of twelve closed trades. Seven won, returning, in euros, 120, 90, 200, 60, 150, 80 and 100. Five lost: 70, 110, 40, 130 and 60. The win rate looks healthy, seven out of twelve, about 58%, but profit factor ignores it and goes straight to the totals.
Winners: 120 + 90 + 200 + 60 + 150 + 80 + 100 = €800 gross profit. Losers: 70 + 110 + 40 + 130 + 60 = €410 gross loss. Profit factor: 800 ÷ 410 = 1.95. For every euro lost in the month, the strategy brought back almost two.
A profit factor of 1.95 is just below the border between solid and strong, and a perfectly respectable real world result. Note that we never needed the win rate to reach this verdict. Profit factor compresses the whole month into a single ratio of euros, and that ratio already tells you the strategy is worth keeping. But it does not tell you everything, and this is where its companion metric earns its place.
Profit factor is a ratio; expectancy is an amount in euros. Expectancy answers a different question: how much is the average trade worth? You compute it as net profit divided by the number of trades.
Expectancy = net profit ÷ number of trades How much, on average, each single trade earns (or costs) you
In our example, the net result is 800 minus 410, that is 390 euros over twelve trades, so expectancy is about 32.50 euros per trade. That single number is the most honest basis for comparing two strategies, because it already fuses how often you win with how much you win and lose.
The two metrics answer complementary questions and you want both. Profit factor is the quick "is it working" check, intuitive and unitless, ideal for glancing at a strategy and knowing instantly whether the math adds up. Expectancy is the number for planning: multiply it by how many trades you take in a month and you have a realistic expectation of monthly profit, which profit factor cannot give you because it is blind to frequency. A scalper with a profit factor of 1.4 over 500 trades a month can make more than a swing trader with a profit factor of 2.5 over 15 trades, and only expectancy times frequency reveals it. For how win rate and risk/reward combine to define your edge, that trade off has an article of its own; here the point is simpler: profit factor judges efficiency, expectancy judges return.
Newer traders chase a high profit factor as if bigger were always better. It is not. Beyond about 4.0, a profit factor usually says more about your sample than about your skill. A handful of trades, or a backtest tuned until it shines, can show a profit factor of 6 or 8 that collapses the moment real conditions arrive.
The reason is statistical: with few trades, a single outsized winner inflates the gross profit half of the ratio, and the number looks spectacular without describing anything repeatable. It is the classic signature of overfitting, a strategy fitted to past data that has no edge in the future. The honest target sits in the green of the scale above: a sustainable strategy usually lands between 1.5 and 2.5 on a real, large sample. When you see a much higher number, the right instinct is not excitement but a question: how many trades produced it, and would it survive out of sample? Profit factor is only as reliable as the history behind it, which is the practical reason it belongs in a trading journal that records every trade automatically and not in a backtest run once.
Computed by hand on a spreadsheet, profit factor and expectancy are a chore that goes stale the moment you open the next trade. AlgoTech connects to your MetaTrader 4, MetaTrader 5 or cTrader account in read only mode (encrypted credentials, no orders, no fund movements) and keeps them updated on your real trades, alongside win rate, drawdown, Sortino and the rest. And because the sample matters, each account lives in a separate environment with its own history: so profit factor is read on the right trades, not on an average across different strategies.

Common questions about profit factor and expectancy.
Read profit factor and expectancy together and you have the two numbers that really decide whether a strategy is worth it: one tells you it is efficient, the other tells you how much it returns per trade. Neither needs a high win rate to look good, and both quietly expose the strategies that use it as a trick.
This article is for informational purposes only and does not constitute financial advice. The numerical examples are illustrative. Algotech Srl is not a financial intermediary.