A trading-expectancy calculator estimates the average result per trade from the observed win rate, average win and average loss. The result describes the supplied sample and assumptions; it does not promise the next trade or future performance.
Calculate expectancy
Formula and units
Expectancy = (win probability × average win) − (loss probability × average loss magnitude). All payoff values must use the same unit: money, percentage of capital, points after conversion, or units of initial risk such as R. Mixing units produces a meaningless output.
Use net outcomes consistently
If commissions, spread, slippage and financing are already included in each recorded trade, use net average wins and losses. If the inputs are gross, subtract a separate cost estimate consistently. Do not deduct some costs twice while omitting others.
| Input | Review question |
|---|---|
| Win rate | How were break-even trades and partial exits classified? |
| Average win | Are rare large wins dominating the estimate? |
| Average loss | Are gaps and unusually large losses included? |
| Sample | Does it represent the rule, market and period being evaluated? |
| Cost treatment | Are all outcomes gross or all outcomes net? |
A positive estimate can still be uncertain
Expectancy is a sample mean assembled from estimated probabilities and payoffs. A small sample, dependent trades or a heavy-tailed outcome distribution can make it unstable. Use Trading Strategy Sample Size to assess evidence sufficiency and intervals rather than treating the sign alone as proof.
Break-even trades and multiple outcomes need explicit rules
The simple form uses winners and losers. If the process has break-even outcomes, partial exits or several payoff categories, calculate the weighted average across all mutually exclusive outcomes or use the average of the complete net-return series. State the classification rule before computing the metric.
Compare planned and realized payoff
A planned risk-reward ratio uses entry, stop and target geometry. Realized expectancy uses actual completed outcomes. Differences can reveal execution costs, early exits, stop movement or a target that is rarely reached.
Review sequence
- Clean the trade record and define classifications.
- Choose one unit and use it for every outcome.
- Calculate win rate and average net win/loss.
- Inspect the distribution and influential trades.
- Measure uncertainty and segment only where sample size supports it.
- Compare later out-of-sample and forward results.
- Investigate rule changes instead of hiding them in the aggregate.
Common errors
- Entering average loss as a negative number and subtracting it again.
- Using a target ratio instead of realized average wins.
- Ignoring costs or break-even classifications.
- Calling a positive historical estimate a guarantee.
- Comparing expectancy values expressed in different units.
Trading Expectancy develops interpretation, while Strategy Validation places the metric inside a wider evidence process. Find related resources through MFXG tools.