Trading costs and your risk budget
Work through fees, spread double-counting and a cost-aware position-size example using a fixed cash budget.
Decide what your price inputs already include
The difference between actual entry and exit fill prices already reflects the prices at which you dealt. A bid/ask spread can therefore be embedded in that difference. If you subtract the same spread estimate again as a separate fee, you double-count it. A chart-midprice example has a different basis and may need a spread allowance. Write down which price basis you are using before combining price loss with a cost estimate.
Separate variable and fixed estimates
The position-size tool accepts estimated account-currency costs per lot and a fixed account-currency amount for the modeled trade. These are user inputs, not a lookup of broker charges. Per-lot costs can represent an applicable round-trip commission or an explicit allowance that scales with volume. Fixed costs reserve an amount that does not change with the modeled size. Overnight funding, conversion fees and execution charges depend on provider terms; not every cost is truly fixed or linear.
A complete $100-budget example
Take a hypothetical $10,000 USD balance, a 1% cash budget and a 30-pip EUR/USD stop. A 100,000-unit lot has a $10 pip value. Assume $7 of estimated costs per lot and $2 of fixed costs. The remaining budget after the fixed amount is $98. Modeled cost per lot at the stop is 30 × $10 + $7 = $307. Raw lots are $98 / $307 ≈ 0.319218. At a 0.01-lot step, rounding down gives 0.31 lots.
Check the rounded total, not just the price loss
For 0.31 lots, price loss is 0.31 × 30 × $10 = $93. Per-lot costs total 0.31 × $7 = $2.17. Adding the fixed $2 gives $97.17 of modeled total loss. Rounding up to 0.32 lots would produce $96 + $2.24 + $2 = $100.24, exceeding the stated budget. These are hypothetical charges. No order or fixed entry charge is modeled when zero lots fit. A future fill can still produce a different loss.
Use the P&L tool on the same basis
If a completed hypothetical trade has $99 gross P&L and $9 of costs not already included in that gross figure, net P&L is $90. Enter total known costs once in the Profit & loss tool. For a trade with a $100 planned gross win and a $50 planned price loss, an assumed $5 cost on every outcome changes the amounts to a $95 win and a $55 loss. The mathematical break-even win rate becomes 55 / (95 + 55) = 36.67%, rather than 33.33% before costs. This is not a probability forecast.
Treat unmodeled costs as uncertainty
A future overnight holding period, a gap or a changing spread cannot be reconstructed from a single fee input. A zero in the cost field means no extra cost was entered, not that execution is free. Check your provider’s current schedule and the statement for an actual trade, and record the assumptions with any hypothetical calculation. SanForex does not quote or compare broker prices, and source links are definitions rather than broker recommendations.
Sources and conventions
Examples are hypothetical. Arithmetic follows the formulas documented in our methodology. Broker contract specifications determine actual lot, margin and execution conditions. These sources document definitions and data; a source link does not imply endorsement of SanForex or a trading service.
These materials are prepared with AI assistance and checked against worked examples and deterministic calculation tests where applicable. They are not an expert suitability assessment or investment advice.
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