Position size calculator

How it is calculated

• Amount at risk = balance × risk % ÷ 100
• Loss per 1.00 lot = stop distance × contract size ÷ exchange rate
• Lots = amount at risk ÷ loss per 1.00 lot, then rounded down to the lot step so the risk is not exceeded

Worked example

Balance 10,000 (USD account), risk 1%, stop distance 5.00, 100 oz per lot. Amount at risk = 100. Loss per lot = 5.00 × 100 = 500. Lots = 100 ÷ 500 = 0.20 lots (20 oz). With a 3.00 stop: 100 ÷ 300 = 0.333, rounded down to 0.33 lots, which risks 99 (0.99%). For a GBP account at GBP/USD 1.25, balance 5,000 and 2% risk, a 4.00 stop costs 400 USD = 320 GBP per lot, so 100 ÷ 320 = 0.3125, rounded down to 0.31 lots.

Things to know

• The calculation assumes the stop fills at its price. In fast markets, around data releases or over a weekend gap, the fill can be worse and the loss larger.
• Spread and commission are not included; add them to the stop distance if you want them counted.
• Contract size, lot step, margin rates and quoting conventions vary between providers and account types. The defaults here are common examples; check your provider’s contract specification and use its figures.

Other calculators

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• Risk/reward and breakeven
• Margin and leverage
• Profit and loss
• Drawdown recovery