For a simplified forex calculation, divide the chosen money budget by the loss for one lot at the assumed stop, including proportional commission. Round the result down to the permitted lot increment, then check minimum volume, maximum volume and margin separately. This is an estimate, not a guaranteed loss limit.
Put the inputs in the same units
Choose the amount you want to use as a planning budget; this guide does not prescribe a suitable percentage or amount. Measure the entry-to-stop distance in pips and find the value of one pip for one lot in the account currency. Keep any commission estimate in that same currency.
Check the actual contract rather than assuming that every symbol uses the same lot size or pip convention. Account-currency conversion and instrument calculation models can change the monetary value. The position-size tool accepts your own pip value; it does not fetch current prices or broker specifications.
Calculate the amount for one lot
For this simplified model, the price loss for one lot is stop distance multiplied by pip value per lot. Add the assumed round-trip commission per lot, then divide the chosen budget by that combined amount. Proportional commission is the only extra cost represented in this formula.
Use an execution-to-stop distance that reflects the intended bid/ask prices. If your worksheet instead uses midpoint prices, include an appropriate spread assumption separately. Do not count the same bid/ask difference twice. Fixed minimum fees, financing, gaps, conversion changes and slippage need separate consideration.
A hypothetical USD 50 calculation
Assume a USD 50 planning budget, a 25-pip stop distance, USD 10 per pip for one lot, a USD 7 round-trip commission per lot, and a 0.01-lot increment. These are invented inputs, not Traders Trust prices or a suggested trading plan.
One lot has an assumed cost of USD 257 at the stop: 25 × 10 + 7. Dividing 50 by 257 gives about 0.19455 lot. Rounding down to 0.19 lot gives USD 47.50 of price loss plus USD 1.33 commission, or USD 48.83. The USD 1.17 difference is unused budget under these assumptions, not a reserve that guarantees protection.
- Planning budget
- USD 50.00
- Assumed amount per lot
- 25 × USD 10 + USD 7 = USD 257
- Rounded position
- 0.19 lot
- Assumed price loss
- 0.19 × 25 × USD 10 = USD 47.50
- Assumed commission
- 0.19 × USD 7 = USD 1.33
- Combined estimate
- USD 48.83
Actual execution and costs may differ. A stop order does not guarantee the selected exit price.
Do not round up or confuse size with margin
Round down rather than up when trying to remain within the stated arithmetic budget. If the result falls below the symbol’s minimum volume, the model does not produce a permitted trade within that budget. Increasing the volume to meet a minimum would change the calculation’s premise.
Required margin is a separate check. A size can fit the planning budget but still require more margin than the account has available. Conversely, spare margin is not proof that the potential loss is acceptable. Check other open positions and current account conditions before interpreting the estimate.
Verify the estimate against the platform
Recheck pip or tick value, volume constraints, commission and the assumed entry and stop against the current symbol specification. For software integrations, MetaQuotes documents OrderCalcProfit as an account-currency pre-evaluation; this website does not call that function or connect to your trading account.
A stop can execute away from its requested price, and a position can incur costs omitted by a simple worksheet. Test the mechanics with virtual funds and inspect the resulting history. A calculation cannot determine personal suitability or guarantee that a loss will stay inside the entered budget.
Sources and editorial note
This Traders Trust educational guide explains general mechanics using original, hypothetical scenarios. The sources below support the definitions and platform behaviour. Other providers’ terms do not describe a Traders Trust account. No investment recommendation or personal suitability assessment is provided.
Sources checked 6 November 2026. This is a source-check date, not a claim of publication or professional review. Current account, instrument and execution terms take precedence over an illustration.
- MQL5: Position/Lot Size CalculatorThe relationship between a money budget, stop distance, pip value and calculated size.
- MQL5 Reference: Symbol propertiesTick values, calculation units and configured volume constraints.
- MQL5 Reference: OrderCalcProfitAccount-currency pre-evaluation in the trading platform; this site does not run that function.