Position size calculator
The formula
Position sizing starts from how much you are prepared to lose, not from how much you hope to make.
Position size (units) = amount at risk ÷ (stop-loss in pips × pip value per unit)
Lots = units ÷ 100,000 (or ÷ 100 for gold)
Example: with a $10,000 account, risking 1% ($100) with a 25-pip stop on EUR/USD, where one pip on one unit is worth $0.0001: 100 ÷ (25 × 0.0001) = 40,000 units, or 0.40 lots.
Choosing a risk percentage
Many educational sources suggest risking between 0.5% and 2% of an account on a single trade. The reason is arithmetic: after ten losing trades in a row at 1% risk, an account is down about 10%; at 10% risk, it is down about 65%. Losing streaks happen to everyone. See risk management for traders for more.
Things the calculator cannot know
- Slippage: in fast markets a stop can fill beyond its level, so the real loss may be larger.
- Spreads and fees: these add to the cost of every trade. See trading fees explained.
- Minimum sizes: providers set minimum and step sizes for lots, so you may need to round down.
- Margin: check the position does not use more margin than you are comfortable with, using the margin calculator.
This calculator assumes a US dollar account and uses the prices you enter; it does not fetch live rates.
Frequently asked questions
What is a good risk per trade?
There is no universal answer, but many traders keep risk per trade between 0.5% and 2% of their account so that a run of losses does not do lasting damage.
Should my stop-loss be based on position size?
It is usually the other way round: place the stop where the trade idea is proven wrong, then size the position so that distance risks only your chosen amount.