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FX Handbook

Position Size Calculator

A position size calculator tells you how many lots to trade so that, if your stop loss is hit, you lose exactly the amount you chose to risk. Enter your account balance, risk percentage and stop-loss distance in pips.

How position size is calculated

Position size
units = risk amount ÷ (stop loss in pips × pip value per unit)

The risk amount is your account balance multiplied by your risk percentage. Pip value per unit is the pip size (0.0001, or 0.01 for JPY pairs) converted into your account currency. Divide units by 100,000 to get standard lots.

Worked example

Balance $10,000, risk 1% ($100), stop loss 20 pips on EUR/USD (USD account):

$100 ÷ (20 × $0.0001) = 50,000 units = 0.50 lots.

Frequently asked questions

How do I calculate position size in forex?

Decide how much money you are willing to lose on the trade (for example 1% of your account), measure the distance to your stop loss in pips, then divide the risk amount by the stop distance multiplied by the value of one pip per unit.

How much should I risk per trade?

Many traders risk between 0.5% and 2% of their account per trade. Keeping risk small means a losing streak does not destroy the account.

What if my broker only allows 0.01 lot steps?

Round the calculated position size down to the nearest lot step your broker allows, so your real risk stays at or below your target.

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Other tools

Results are estimates for educational purposes and exclude spreads, commissions and swaps unless stated. Always confirm figures with your broker before trading.