Trade expectancy is the average amount a strategy makes or loses per trade, expressed as a multiple of the amount risked (R), and it is the single number that actually tells you whether a strategy is profitable - win rate alone does not. The formula is expectancy = (win rate × average win in R) − (loss rate × average loss in R). A strategy that wins 30% of the time but makes 3R on every win and risks 1R on every loss has an expectancy of +0.2R per trade, exactly the same as a strategy that wins 60% of the time trading 1:1 - two very different-looking track records with an identical edge. The reverse also holds: a strategy that wins 70% of the time can still have negative expectancy if what it risks on the losers dwarfs what it makes on the winners. Win rate is the number people quote because it feels intuitive; expectancy is the number that actually decides whether trading the strategy, over enough trades, makes money or loses it.
The formula
Expressed in R-multiples (a trade's profit or loss divided by the amount that was risked on it), expectancy per trade is:
expectancy = (win rate × average win) − (loss rate × average loss)
A positive result means the strategy makes money on average, per trade, over enough trades. A result at or below zero means it does not - no matter how good any individual trade or short stretch looked.
The same edge can look completely different
| Win rate | Reward : risk | Expectancy per trade |
|---|---|---|
| 30% | 3 : 1 | +0.20R |
| 40% | 2 : 1 | +0.20R |
| 60% | 1 : 1 | +0.20R |
| 50% | 1 : 1 | 0.00R |
| 50% | 2 : 1 | +0.50R |
| 70% | 0.25 : 1 | −0.125R |
The first three rows have nothing in common on the surface - a scalper's 60% win rate, a swing trader's 40%, a trend-follower's 30% - and identical expectancy underneath. The last row shows the trap directly: a 70% win rate, the kind of number that gets screenshotted and shared, paired with a reward-to-risk ratio that quietly makes it a loser.
Why win rate alone is the wrong headline
Win rate answers "how often," not "how much." A strategy's profitability depends on both, multiplied together in exactly the way the formula does it - reporting one without the other is like describing a car's trip only by how many turns it made. This is also why the break-even win rate for a given reward-to-risk ratio is really the same formula solved for the point where expectancy hits exactly zero - a 2:1 reward-to-risk strategy breaks even at a 33.3% win rate for the same reason a 30%-win-rate, 3:1 strategy shows positive expectancy above.
Positive expectancy is not a guarantee, trade to trade
Expectancy describes the average over many trades, not the outcome of any particular one. A genuinely positive-expectancy strategy can still produce a real losing streak and a real drawdown along the way - the math in what drawdown is and the recovery math applies just as much to a strategy with a sound edge as to one without. That's why expectancy and position sizing are two separate questions: expectancy tells you the strategy is worth trading at all; position sizing decides how large to trade it so a normal losing streak stays survivable.
Using it in practice
Compute expectancy from real trade history or a real backtest, not from an entry rule's theoretical win rate alone - the average win and average loss have to reflect the same slippage, spread, and stop-out behavior the strategy actually experiences. A small positive expectancy is not automatically worth trading either: it still needs enough trade frequency to compound into a meaningful return, and enough of a sample to trust that the win rate and average win/loss are stable rather than a lucky stretch.
Common questions
What is expectancy in trading?
Expectancy is the average amount a strategy makes or loses per trade, expressed as a multiple of the amount risked (R). It combines win rate and reward-to-risk into one number: expectancy = (win rate x average win in R) - (loss rate x average loss in R).
Can a strategy with a low win rate still be profitable?
Yes. A strategy that wins only 30% of the time with a 3:1 reward-to-risk ratio has an expectancy of +0.2R per trade - the same as a 60% win-rate strategy trading 1:1. Win rate and reward-to-risk trade off against each other, and expectancy is what tells you whether the combination actually works.
Can a high win rate strategy still lose money?
Yes. A strategy that wins 70% of the time but makes only 0.25R on each win while losing 1R on each loss has an expectancy of -0.125R per trade (0.7 x 0.25 - 0.3 x 1) - it loses money on average despite winning most of the time, because each loss costs four times what each win pays.
Is a positive expectancy strategy guaranteed to be profitable?
Not on any given stretch of trades. Expectancy describes the average outcome over many trades - a positive-expectancy strategy can still produce a losing streak and a real drawdown along the way, which is why position sizing and drawdown limits matter even when the expectancy itself is sound.