Across win rate, profit factor, recovery factor and drawdown, one theme keeps showing up: no single statistic tells the whole story on its own.
A strategy can have an excellent win rate and still lose money. It can have a strong profit factor and still carry a drawdown nobody could sit through. Judging a system properly means looking at several of these numbers together.
Expectancy is the closest thing to an exception. It’s a single figure built directly from win rate and average win/loss size, and it answers the one question underneath all the others: on average, what should you actually expect to make or lose per trade?
Get this number right, and everything else — position sizing, how many trades you need, whether a strategy is worth running at all — follows from it.
What Is Expectancy?
Expectancy is the average result you can expect from a single trade, calculated across a strategy’s full history:
Expectancy = (Win Rate × Average Win) – (Loss Rate × Average Loss)
It can be expressed in pips, in your account currency, or as a percentage of account risk per trade — whichever unit you use, keep it consistent throughout the calculation.
A positive expectancy means the strategy makes money on average over a large enough number of trades.
A negative expectancy means it loses money on average, no matter how good any individual win rate or profit factor figure looks in isolation.
A Worked Example
Suppose a strategy has produced 100 trades: 42 winners averaging 65 pips each, and 58 losers averaging 30 pips each.
- Win rate: 42%
- Loss rate: 58%
- Average win: 65 pips
- Average loss: 30 pips
Expectancy = (0.42 × 65) – (0.58 × 30) = 27.3 – 17.4 = 9.9 pips per trade
On average, each trade this strategy takes is worth roughly 9.9 pips. Over 100 trades, that works out to a theoretical total of around 990 pips — before spread, commission and slippage are deducted, all of which reduce this figure in practice and need to be accounted for separately.
Why Expectancy Beats Win Rate or Profit Factor Alone
Win rate tells you how often a strategy wins, but nothing about size. Profit factor tells you the ratio of total money won to total money lost, but doesn’t translate easily into what a single trade is actually worth to you.
Expectancy folds both pieces of information into one number, expressed per trade, which makes it far more directly useful for two practical questions: is this strategy worth trading at all, and how much should I risk on each trade given what a typical one is worth?
Two strategies can have wildly different win rates and profit factors while landing on a very similar expectancy — and a similar expectancy means a broadly similar long-run outcome, however differently the two strategies get there.
From Per-Trade Expectancy to Real Returns
Expectancy is an average, not a guarantee for any individual trade. A strategy with a positive expectancy can still lose money on any given trade, or string together several losses in a row — the edge only expresses itself reliably over a large enough number of trades, in line with the same law of large numbers that applies to any repeated probabilistic process.
This is why a strategy with strong expectancy calculated from only 20 or 30 trades deserves far less confidence than one built on several hundred. A handful of trades can easily produce a flattering or unflattering expectancy purely by chance, before the strategy’s real long-run average has had a chance to show itself.
Common Mistakes When Calculating Expectancy
- Ignoring trading costs. Spread, commission and swap all reduce real-world expectancy compared with a theoretical pip-based calculation. A strategy with a thin positive expectancy on paper can easily be a net loser once costs are included.
- Using too small a sample. Expectancy from a handful of trades is closer to noise than signal. Look for a large enough sample to have genuine confidence in the average.
- Mixing units inconsistently. Pips, currency amounts and percentage-of-account figures aren’t interchangeable without proper conversion, particularly across different position sizes or instruments.
- Letting a few outlier trades dominate the average. One unusually large winning or losing trade can distort expectancy significantly. It’s worth checking whether the figure still holds with and without the biggest outliers included.
- Treating backtested expectancy as fixed. Like every other statistic covered in this series, expectancy calculated from a backtest or a short live period is a snapshot, not a promise — market conditions change, and a strategy’s real edge can drift over time.
How Expectancy Ties the Other Statistics Together
Expectancy, win rate, profit factor, recovery factor and drawdown all describe the same underlying set of trades from different angles.
Win rate tells you how often you’ll be right. Profit factor tells you the ratio of total gains to total losses. Expectancy converts that into a single average value per trade.
Drawdown and recovery factor then tell you what the ride to get that average actually looks like — how much pain sits between you and the long-run result expectancy predicts.
A strategy worth trusting with real money should hold up reasonably well across all of these, not just the one being advertised on a sales page.
A positive expectancy paired with a manageable drawdown and a large enough sample size is a genuinely strong signal.
A positive expectancy built on 25 trades with an unstated staking method is not.
Key Takeaways
Expectancy tells you what a strategy is actually worth, per trade, on average — the figure that win rate and profit factor are really just partial views of. Before trusting any strategy, robot or signal service, work out its expectancy using real costs and a large enough sample of trades, and read it alongside drawdown to understand what achieving that average will actually feel like to trade through.
This article is for educational purposes and does not constitute financial advice. Trading forex carries a high level of risk and may not be suitable for all investors.
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