Trade sizing
Position size calculator
Position sizing turns a risk rule, such as risking 1% of the account per trade, into a concrete lot size. It uses your balance, the percentage you are prepared to lose, the distance to your stop-loss and the pip value of the instrument. The calculated lot size is rounded down; costs, slippage and execution gaps can still increase the actual loss.
Result
- Position size
- 0.20 lots
- Units
- 20,000 base units
- Amount at risk
- 100.00 USD
How it is calculated
Amount at risk = balance × risk % ÷ 100Lots = amount at risk ÷ (stop-loss in pips × pip value per lot in account currency)
Worked example
Balance 10,000 USD, risk 1% (100.00 USD), EUR/USD with a 50-pip stop-loss. One lot is worth 10 USD per pip, so 50 pips cost 500 USD per lot: 100 ÷ 500 = 0.20 lots.
Assumptions and practical examples
Read the result in three steps: choose the monetary amount at risk, calculate the loss per lot over the stop distance, then divide the first by the second. Illustrative USD/JPY example: at 1,000 JPY per pip per lot, a 50-pip stop is 50,000 JPY per lot. A 10,000 JPY risk allowance therefore gives 0.20 lots before costs.
The displayed rounding is not a check of your broker's permitted lot step or minimum order. Confirm those separately. Stops can execute beyond the requested price; costs and slippage mean a planned risk amount is not a loss limit.
Questions
Why is the result rounded down?
Rounding up would make the loss at the stop-loss slightly larger than the amount you chose to risk. Rounding down keeps it at or below that amount.
What is a standard lot?
For forex, one standard lot is 100,000 units of the base currency, a mini lot is 10,000 and a micro lot is 1,000 (0.10 and 0.01 lots).
Does this include spread and commission?
No. Spread, commission and slippage add to the loss when a stop-loss is hit, so the real loss can be a little larger than the amount shown.
Results are estimates for education; your broker's contract specification and prices decide the real values. Trading leveraged products carries a high risk of losing money.