Position Size Calculator
Work out the exact lot size for any trade from your account balance, the percentage you are willing to risk and your stop-loss distance.
How to use the position size calculator
Enter your account balance, the percentage of it you are willing to lose if the trade hits its stop, the stop-loss distance in pips and the pip value for one standard lot. The calculator returns the amount at risk, the position size in lots and the same size in units.
For pairs quoted in US dollars, such as EUR/USD or GBP/USD, one standard lot is worth $10 per pip. For other pairs, get the exact figure from the pip value calculator first.
The position size formula
Lot size = (balance × risk %) ÷ (stop-loss in pips × pip value per lot)
Example: a $10,000 account risking 1% has $100 at risk. With a 25-pip stop on EUR/USD, each standard lot loses $250 if the stop is hit (25 × $10), so the correct size is $100 ÷ $250 = 0.40 lots, or 40,000 units.
How much should you risk per trade?
Many traders risk between 0.5% and 2% of their account on each trade. Small, fixed risk keeps a losing streak survivable: ten losses in a row at 1% risk cost about 9.6% of the account, while ten losses at 5% cost about 40%. Prop firm traders often risk less because of daily loss limits. Read more in our position sizing course.
Common position sizing mistakes
- Choosing the lot size first and the stop second. Set the stop where the trade idea is wrong, then size the position to fit.
- Using the wrong pip value for cross and JPY pairs.
- Forgetting that spread and commission add to the real loss when a stop is hit.
- Raising risk after a loss to win it back quickly.
Frequently asked questions
How do I calculate position size in forex?
Multiply your balance by your risk percentage to get the dollar amount at risk, then divide by the stop-loss in pips multiplied by the pip value per lot. The result is your position size in lots.
What is a good risk per trade?
Many traders risk 0.5% to 2% of their account per trade. Lower risk means smaller swings and a better chance of surviving a losing streak.
Does the position size change with the stop-loss?
Yes. A wider stop needs a smaller position to keep the dollar risk the same, and a tighter stop allows a larger one.
Is this calculator free?
Yes. It is free, works in your browser and needs no sign-up.