Trading expectancy

Expectancy is the average amount you win or lose per trade, averaged over a large sample. It rolls your hit rate and your payoff sizes into a single number that answers the only question that matters over the long run: does this edge make money? A positive expectancy means the system pays you to trade it; a negative one means it drains you no matter how good any individual trade felt. It is a per-trade figure, so you read it alongside how many trades you actually take.

How it's calculated

Expectancy combines how often you win with how much you win and lose. The formula:

Say you win 40% of your trades. Your winners average $600 and your losers average $300. Loss rate is the other 60%.

• Winning side: 0.40 × $600 = $240
• Losing side: 0.60 × $300 = $180
• Expectancy: $240 − $180 = $60 per trade

So even though you lose more often than you win, every trade you take is worth $60 on average. Over 500 trades that is $30,000 of expected profit, before you touch position sizing.

You can also express expectancy in R-multiple terms, where 1R is the amount you risked on the trade. If your average winner is +2R and your average loser is −1R, the same math gives (0.40 × 2R) − (0.60 × 1R) = 0.20R per trade. Working in R decouples the edge from dollar size, so you can compare a scalping system against a swing system on equal footing.

Why it matters

A small positive expectancy is still an edge, and edges compound. That $60-per-trade system doesn't look like much next to a single lucky $2,000 winner, but it doesn't rely on luck — it grinds forward every time you pull the trigger. The trader chasing home-run trades with negative expectancy goes broke slowly; the disciplined trader with $60 of edge and 800 trades a year does not.

Sample size is what turns expectancy from a story into a fact. Over 20 trades, variance dominates and a positive-expectancy system can easily show a loss. Over 300+ trades, the average converges and the edge shows up in your equity curve. Never size a system, or kill one, off a handful of trades — you're reading noise, not signal.

Expectancy also anchors your risk. Once you trust the per-trade edge, position sizing decides how fast it compounds and how likely you are to survive the drawdowns along the way. Size too aggressively and a normal losing streak can wipe out an account that had a genuine edge — that's the link between expectancy and risk of ruin. The goal is to bet enough to let a positive expectancy work, but not so much that variance ends the game before the math pays off.

To pressure-test a system before you risk capital, run your numbers through the trading expectancy calculator and watch how sensitive the result is to small changes in your hit rate or payoff ratio.

Related concepts

Expectancy is built from the two inputs every trader tracks: your win rate and your average win / average loss. Neither number means much alone — a 30% win rate is fine with a big payoff ratio, and an 80% win rate can still lose money if your losers dwarf your winners. Expectancy is where they meet.

It's closely related to profit factor, which expresses the same edge as a ratio of gross profit to gross loss rather than a per-trade dollar figure. Track all of these together on your Tradeways dashboards so you're judging your system on its real, sample-weighted edge instead of your memory of the last few trades.