Positive expectancy means the inputs imply an average gain per trade before unmodeled costs. It is only as reliable as the sample and assumptions behind the numbers.
Tools / Calculator
Trading Expectancy Calculator
Estimate the average result implied by your win rate, average winner, and average loser.
EXPECTANCY
Average per trade+0.35R
Across sample+35.00R
(Win rate × average win) − (loss rate × average loss).
A 45% win rate with an average +2R winner and −1R loser implies +0.35R per trade before additional costs.