Risk Academy

Expectancy: Why Win Rate Lies

Win rate is the most seductive number in trading — it's the one your brain feels after every session, and the one every screenshot advertises. It is also, by itself, meaningless. A 90% win rate can bankrupt you. A 35% win rate can pay your rent. The number that decides which is called expectancy, and it fits on a napkin.

The napkin formula

E = (win% × avg win) − (loss% × avg loss)

Measured in R— your fixed risk unit from the position sizing guide. E is what one average trade pays you, before it happens. Positive E compounds; negative E just hasn't finished yet.

Two traders, same market

  • Profile A — the comfortable loser

    Wins 90% of trades, but takes profit at +0.2R ('lock it in') and lets losers run to −3R ('it always comes back'). E = 0.90×0.2 − 0.10×3.0 = −0.12R per trade. He is losing money and feels fantastic — 9 green days out of 10, right up until the day that deletes two weeks.

  • Profile B — the uncomfortable winner

    Wins 35% of trades at +2.5R, cuts losers at −1R, every time. E = 0.35×2.5 − 0.65×1.0 = +0.225R per trade. Over 100 trades that's ~22R — at $60 R on a funded account, $1,300+ of edge. She loses most days and feels like a failure while getting paid.

A: wins 90% of days — feels like geniusone 3R day erases 15 winsB: loses most days — pays every monthSame market, 100 trades each. Your feed is full of A's screenshots. The payout lists are full of B.
Profile A: 90% win rate, negative expectancy — smooth until the cliff. Profile B: 35% win rate, positive expectancy — ugly daily, beautiful yearly.

The part nobody prepares for: streaks

Profile B's edge comes with a bill: at a 35% win rate, a streak of 6–8 straight losses inside 100 trades is normal math, not a broken strategy.

That's the hidden link to sizing: at 1R = 2% of your real account, an 8-loss streak costs 16% — unpleasant, survivable. At 5% R it costs 40%, and on a funded account the daily loss limit probably ended the story at streak four.

Positive expectancy only pays people who can afford to still be there when it averages out. Sizing is what buys the ticket.

Where traders fall

  • They optimize for win rate because it optimizes for mood — moving stops, cutting winners early. Every 'improvement' raises win% and lowers E.
  • They judge a strategy on 15 trades. At 35% win rate, 15 trades can easily contain zero wins in a row of any signal — E needs a 50–100 trade sample.
  • They quit Profile B strategies during the normal streak, right before the math pays — then buy Profile A courses because the screenshots look smoother.
  • They track dollars instead of R, so a lucky oversized win hides a negative-E process for months.

Compute yours tonight

  • Export your last 50+ trades. Convert each P&L to R (P&L ÷ what 1R was that day).
  • Compute: win%, average win in R, average loss in R → plug into the napkin formula.
  • If E is negative, look at the two levers separately: are winners dying young (avg win < 1R), or are losers living too long (avg loss > 1R)? Fix the bigger lever first.
  • Re-run monthly. Expectancy drift is how strategies quietly die — and how you catch it before the account does.

E is per trade — costs are per trade too

The Real Cost of a TradePosition Sizing Guide

Educational content only — not financial advice.