Trading Expectancy Explained — Why Win Rate Alone Means Nothing
Most traders obsess over their win rate. Hit 60%, 70%, 80% and you must be profitable — right? Wrong. Win rate without context is meaningless. A 40% win rate can generate more profit than a 70% win rate. The number that actually tells you whether your strategy makes money is your expectancy.
What is Trading Expectancy?
Expectancy is the average amount you expect to make per dollar risked over a large sample of trades. The formula is:
A positive expectancy means your strategy makes money over time. A negative expectancy means you will lose money regardless of how disciplined you are — the strategy itself is broken.
Win Rate vs Expectancy — A Real Example
Consider two traders:
- Trader A — 70% win rate, average win $100, average loss $300. Expectancy = (0.70 × $100) − (0.30 × $300) = $70 − $90 = −$20 per trade (losing strategy)
- Trader B — 40% win rate, average win $400, average loss $150. Expectancy = (0.40 × $400) − (0.60 × $150) = $160 − $90 = +$70 per trade (winning strategy)
Trader A wins 70% of the time and loses money. Trader B wins only 40% of the time and makes $70 per trade on average. Win rate alone tells you nothing.
What is the Breakeven Win Rate?
The breakeven win rate is the minimum win percentage needed to be profitable at your current risk/reward ratio. The formula is: Average Loss ÷ (Average Win + Average Loss). At a 2:1 R:R (risking $100 to make $200), your breakeven win rate is $100 ÷ $300 = 33.3%. You only need to win 1 in 3 trades to break even.
Expectancy and Prop Firm Evaluations
Understanding your expectancy is critical for prop firm trading. Before you pay for an evaluation, calculate whether your strategy has positive expectancy over at least 50 trades. A strategy with positive expectancy will pass evaluations given enough time and consistent execution. A strategy with negative expectancy will fail no matter how good your risk management is.