Trading cost and break-even sensitivity calculator
Small execution costs can consume a large fraction of a tight stop. Convert spread, slippage, commission and financing into money and R, then see how they affect expectancy and the break-even win rate. Use measurements from your own execution records.
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Processing stays in your browser. No account or upload is required. Results depend on your inputs and are educational calculations rather than investment advice.
Put every cost in the same units
Position pip value = lots × contract units × pip size × quote-to-account rate.
1R = stop distance in pips × position pip value.
Net round-trip cost = (additional spread + adverse slippage) × position pip value + commission per lot × lots − signed whole-position financing.
Cost in R = net round-trip cost ÷ 1R.
Gross expectancy = p × average winning R − (1 − p) × average losing R.
Net expectancy = gross expectancy − cost in R.
Break-even win rate = 100 × (average losing R + cost in R) ÷ (average winning R + average losing R).
These formulas apply a constant average cost to every trade, winning or losing. Financing credits can make the net cost negative. A break-even threshold above 100% means no feasible hit rate breaks even under those assumptions. A planned take-profit ratio does not establish the realised average winning outcome or hit rate.
Avoid counting a cost twice
If entry and exit prices are actual fills, spread is usually already reflected in them. If journal averages are already net of the entered costs, choose Already net: the cost budget remains visible, but it is not deducted from expectancy again. Sensitivity is then disabled because adjusting a cost already embedded in outcome averages requires reconstructing the matching gross outcomes.
The sensitivity table keeps win rate and payoff multiples fixed while changing one cost assumption or the monetary stop-risk denominator. Changing a real stop can also change hit rate and realised payoffs. The table is an arithmetic comparison, not a suggestion to widen or tighten a stop. Totals across trades use constant monetary R and no compounding.
Worked example
One 100,000-unit EUR/USD lot on a USD account has a 10 USD pip value. A 20-pip stop defines 200 USD as 1R. One pip of additional spread, one pip of adverse slippage, 5 USD round-trip commission and −2 USD financing produce 27 USD net cost, or 0.135R. At 45% wins, a 2R average win and a 1R average loss, gross expectancy is 0.35R, net expectancy is 0.215R and the break-even win rate is 37.83%.
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Method and tool reviewed 26 October 2026. Editorial methodology · About the author
