Expectancy vs Win Rate: Why a High Win Rate Can Lose
Win rate is simply the percentage of your trades that make money, while expectancy is the average dollar amount you can expect to win or lose per trade once you factor in both how often you win and how big your wins are versus your losses. The key insight is that a high win rate alone doesn't mean you're profitable. You can win 90% of the time and still lose money if the occasional loss is huge. You can also win only 35% of the time and do great if your winners dwarf your losers, which is how many trend-following strategies work. Expectancy is the truer measure because it blends both pieces into one number. The simple formula is (win rate times average win) minus (loss rate times average loss). Judge a strategy on expectancy, not on win rate by itself.
A strategy can win often and still lose money if the losers are large. How expectancy combines win rate and average win and loss into a more honest measure.
Key points
- Win rate is the share of your trades that end in a profit, and nothing more.
- Expectancy is the average profit or loss you can expect per trade once win size and loss size are included.
- A high win rate can still lose money if the rare losses are much bigger than the frequent wins.
- A low win rate can be very profitable when the winners are far larger than the losers, which is common in trend following.
- The formula is (win rate times average win) minus (loss rate times average loss), and a positive result means a net edge per trade.
- Because expectancy blends how often and how much, it's the more honest way to judge a strategy than win rate alone.
Frequently asked questions
Is a high win rate good?
Not by itself. Winning often feels great, but if your few losses are large enough, they can wipe out many small wins and leave you negative. Win rate only tells half the story; you also need to know how big the wins and losses are.
How do I calculate expectancy?
Use (win rate times average win) minus (loss rate times average loss). For example, if you win 40% of trades with an average win of $200, and lose 60% with an average loss of $100, expectancy is (0.40 times 200) minus (0.60 times 100), which is $80 minus $60, or $20 per trade.
Can I be profitable with a low win rate?
Yes. Plenty of trend-following approaches win only 30% to 40% of the time yet make money, because their winners are several times the size of their losers. As long as expectancy is positive, a low win rate can still add up over many trades.
What's a good expectancy?
Any positive expectancy means you have an edge per trade, but bigger is better and steadier is safer. Just remember expectancy is an average, so a positive number over few trades can still be luck. You want a positive figure backed by a large sample of trades.
Where do I see win rate and expectancy in Agenticks?
When the AlgoAgent backtests a strategy, it reports win rate, average win, average loss, and the resulting expectancy together, so you can see whether the edge holds up. You ask the agent to run the test, and it breaks these numbers down for you in plain language.
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This content is for educational purposes only and does not constitute financial advice. Trading involves risk, including possible loss of capital.