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Tool / risk maths
Trading position size calculator
This position size calculator translates a planned cash risk into a simple number of units. It helps you see how stop distance changes size. The estimate is not a guarantee: contract multipliers, fees, slippage, minimum order sizes and currency conversion can change real outcomes.
Runs in your browserNo account · No API key
local only
How to use it
Numbers are clearer when the assumptions are visible.
Start with the default example. Change one input at a time and notice which part of the result moves. Then read the explanation below before using any real-world number.
- Use your account currency consistently.
- Include costs and uncertainty outside the simple model.
- Verify the product’s own contract or fee rules.
The learning formula
The calculator first multiplies account balance by risk percentage to get a cash risk budget. It then divides that budget by the absolute distance between entry and stop. If the stop is five price units away and the budget is 50, the simple position size is 10 units.
This approach assumes one unit loses one price unit for every one-unit move and does not handle forex pip values or contract multipliers. Use the separate pip calculator for a basic forex estimate.
Working modelUnits = (balance × risk %) ÷ |entry − stop|
Before using a calculated size
Check whether the market allows fractional units, what one contract represents and whether the account currency matches the quote currency. Round down when an increment is required. If the minimum order is larger than your safe size, reduce the planned risk, choose a different instrument or practise without placing the trade.
A position-size number cannot repair a weak setup. It only limits the amount attached to the invalidation you define.
- Confirm minimum order and tick size.
- Add fees and slippage to the risk estimate.
- Check leverage and notional exposure separately.
- Never move the stop farther away to justify size.
Common questions
Before you move on
What if the stop is above the entry?+
The calculator uses the absolute distance, so it can model long or short examples. The direction and product rules still need to be checked separately.
Does it calculate leverage?+
No. It calculates simple units from risk. Review notional value, margin and leverage with the venue’s own rules.
Should I round up or down?+
For a risk limit, rounding down is generally the conservative direction, subject to the product’s rules.