Trading Expectancy Explained: The One Number That Tells You If Your Strategy Works

Ask most traders if their strategy is profitable and they’ll tell you about their last few trades, their best month, or their win rate. None of these actually answer the question.

The number that answers it is expectancy — and most traders have never calculated it.

What Is Trading Expectancy?

Expectancy is your average expected return per trade. It combines your win rate, average win size, and average loss size into a single number that tells you whether your strategy has a mathematical edge.

The formula:

Expectancy = (Win Rate × Average Win) - (Loss Rate × Average Loss)

Or equivalently:

Expectancy = (Total Net P&L) / (Total Number of Trades)

If your expectancy is positive, you make money over time. If it’s negative, you lose money over time — regardless of your win rate.

Why Win Rate Alone Is Misleading

Here’s a scenario that breaks most traders’ intuition:

Trader A: 70% win rate
- Wins: 70% of trades, average win $50
- Losses: 30% of trades, average loss $200
- Expectancy: (0.70 × $50) - (0.30 × $200) = $35 - $60 = -$25 per trade

Trader B: 35% win rate
- Wins: 35% of trades, average win $300
- Losses: 65% of trades, average loss $80
- Expectancy: (0.35 × $300) - (0.65 × $80) = $105 - $52 = +$53 per trade

Trader A wins most of their trades but loses money. Trader B loses most of their trades but makes money. This is why chasing a high win rate without managing the win/loss ratio is a losing strategy.

How to Calculate Your Expectancy

Step 1: Gather Your Trade Data

You need at least 50-100 trades for a meaningful expectancy calculation. Fewer trades and the number is too noisy to be useful.

Export your trade history from your broker and calculate:
- Total trades (N)
- Winning trades (W)
- Losing trades (L)
- Total profit from winners (Σ wins)
- Total loss from losers (Σ losses)

Step 2: Calculate Components

Win Rate = W / N
Loss Rate = L / N (= 1 - Win Rate)
Average Win = Σ wins / W
Average Loss = |Σ losses| / L

Step 3: Calculate Expectancy

Expectancy = (Win Rate × Average Win) - (Loss Rate × Average Loss)

Step 4: Calculate Profit Factor

While you’re at it, calculate profit factor:

Profit Factor = Σ wins / |Σ losses|

• PF > 1.0: profitable
• PF > 1.5: solidly profitable
• PF > 2.0: very strong
• PF < 1.0: losing money

Example Calculation

Let’s say over 200 trades:
- 110 winners with total profit of $8,800
- 90 losers with total loss of -$6,300

Win Rate = 110/200 = 55%
Loss Rate = 90/200 = 45%
Average Win = $8,800/110 = $80
Average Loss = $6,300/90 = $70

Expectancy = (0.55 × $80) - (0.45 × $70) = $44 - $31.50 = +$12.50 per trade

Profit Factor = $8,800 / $6,300 = 1.40

This strategy makes an average of $12.50 per trade. Over 200 trades, that’s $2,500. Not amazing, but definitively profitable.

What Your Expectancy Tells You

Positive Expectancy (+$X per trade)

You have a statistical edge. The larger the number relative to your average position size, the stronger your edge. Key question: is your edge large enough to survive fees, slippage, and real-world conditions?

Zero or Near-Zero Expectancy