The expectancy calculation
Multiply the win probability by the average winning amount, subtract the loss probability multiplied by the average losing amount, then subtract costs. Keep all payoff and cost inputs in the same R unit.
At a 40% win rate, average win of 2R and average loss of 1R, the pre-cost expectancy is 0.2R per trade. A cost of 0.05R reduces the scenario expectancy to 0.15R.
Why sample quality matters
Estimated win rates and payoffs can be unstable when based on a small or selectively chosen sample. Average results can also hide extreme losses, changing market conditions and correlated trades. The calculator does not produce a confidence interval or validate your trade sample.
The projected total is the per-trade arithmetic expectation multiplied by the supplied trade count. It does not compound account equity or simulate the order in which wins and losses occur.
Costs need consistent treatment
Include fees and expected execution costs only once. If your average win and loss already come from net trade records, adding those same costs again would double-count them. If you define one R using a planned stop, actual losses can still exceed one R during gaps or failed exits.
Questions about this tool
Does positive expectancy guarantee a profitable month?
No. Even a correctly estimated positive expectation can produce losing sequences. This tool does not model outcome distributions.
Should I enter win rate as a fraction?
Enter a percentage, such as 40 for 40%. Payoffs and costs use R multiples.