How do I calculate forex position size?

Lots = money you're willing to risk divided by (stop-loss in pips times pip value per lot). Risking 100 dollars with a 20-pip stop on EUR/USD (10 dollars per pip per lot) gives 100 / (20 x 10) = 0.50 lots.

Why is the result rounded down?

Brokers only accept sizes in fixed steps, usually 0.01 lots. Rounding down keeps the money at risk at or below your limit.

Forex position size calculator

Work out how many lots to trade so that, if your stop-loss is hit, you lose no more than the share of your balance you chose. Everything is calculated in your browser.

Your account and trade

Account currency

Currency pair

Account balance (USD)

Risk per trade (% of balance)

Stop-loss distance (pips)

Pair price

Filled in from daily reference rates. Type your broker's price for exact figures.

Contract size, lot step and minimum lot

Contract size (units per 1 lot)

100,000 is the common standard lot. Check your broker's contract specs.

Lot step

Minimum lot

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How the position size formula works

Lots = money at risk ÷ (stop-loss in pips × pip value per lot)

Example: a 10,000 US-dollar account risking 1% puts 100 dollars at risk. On EUR/USD one pip is worth 10 dollars per standard lot, so a 20-pip stop costs 200 dollars per lot. 100 ÷ 200 = 0.50 lots.

The size is rounded down to your broker's lot step so the money at risk stays within your limit. Spreads, commission, financing and slippage (prices can gap past a stop, especially around news) all add to the real loss.

Need the pip value on its own? Use the pip value calculator. For gold, use the gold lot size calculator on Gold Desk.