Position size and stop distance: calculation inputs

The essentials

A distance's monetary effect depends on size and value per movement unit. Include spread, commission and possible slippage. Ordinary stops do not guarantee exact execution, so an estimate is not a loss ceiling.

Understand the mechanism, not just the definition

Calculate size from monetary sensitivity and price distance, not free margin. Define movement units and value per unit for one lot, then add known costs and permitted volume steps. A theoretical stop-based calculation does not guarantee realized loss because execution and gaps can change the close.

Example and verification

Hypothetical example: 20 pips at USD 2 per pip produce USD 40 before costs. Adding USD 6 commission yields USD 46 without conversion or slippage. Doubling pip value doubles the distance's effect.

Worked case, step by step

Use a hypothetical USD 50 budget, 25-pip distance, USD 10 per pip per lot and USD 7 round-trip cost per lot. One lot’s modeled stop cost is USD 257; 50/257 is about 0.1945 lot. At a 0.01 step, rounding down to 0.19 models USD 48.83. This illustrates arithmetic, not a recommended budget or guaranteed close.

What to verify when applying this

Check specifications and minimums before setting size. Do not force a trade when the contract minimum exceeds your scenario. Compare monetary exposure, not lots; educational arithmetic is not personalized risk advice.

Practice: verify it in your environment

Learn by observing the process and keeping its data. Complete this practice in demo or using documentation, without sending real orders or adding capital for the exercise. Record differences between the example and your account specifications.

1. Convert distance to the unit used by monetary sensitivity.
2. Document costs, rounding and stop limitations before interpreting the result.

Test your understanding

Try the question before revealing the answer. Justify the conclusion and its assumptions rather than memorizing a number.