Position size calculator
Work out the lot size for a trade from your balance, the amount you are willing to lose and the stop-loss distance.
Result
- Lot size (rounded down to the step)
- Exact value before rounding
- Amount at risk
- Loss at the stop-loss with this lot size
- That loss as a share of the balance
- Pip value for 1 lot
Enter the exchange rate to your account currency.
Enter the contract size.
Enter the minimum lot and the lot step.
The exact value was rounded down to your lot step, so the loss stays at or under the amount at risk.
The exact value is below the minimum lot, so this trade cannot be placed at this risk. With the minimum lot the loss would be larger than the amount at risk.
- Balance needed for the minimum lot at this risk and stop-loss
Getting exchange rates…
Lots = amount at risk / (stop-loss pips x pip value of 1 lot). The pip value uses the contract size and the exchange rate shown, so a pair that does not include your account currency needs a rate. Choosing “Amount of money” does not need a balance.
These are estimates for working out a trade. They leave out spread, commission, slippage and swap unless a field says otherwise, and every broker rounds lots and calculates margin in its own way. Check the figures on your trading platform. Nothing here is investment advice.
Exchange rates: ExchangeRate-API
What this calculator tells you
This calculator turns a risk limit into a lot size. You give it your balance, how much you are willing to lose on one trade and how far away the stop-loss sits. It returns the largest lot size, rounded down to your broker's lot step, whose loss at the stop stays within that limit.
Worked examples
EURUSD, USD account, balance 10,000, risk 1% (100 USD), stop-loss 20 pips. One pip of one lot is worth 10 USD, so 100 / (20 x 10) = 0.5 lot.
USDJPY, USD account, balance 5,000, risk 2% (100 USD), stop-loss 30 pips, rate 150 yen per dollar. One pip of one lot is worth about 6.67 USD, so the result is 0.5 lot.
Common mistakes and things to check
- Use the pip value in your account currency. When the pair does not contain it, enter the exchange rate; a wrong rate gives a wrong lot size.
- On yen pairs a pip is 0.01, not 0.0001. Check the pip size of the instrument you picked.
- If price gaps or slips past your stop, the real loss can exceed the planned amount. Spread and commission are not included.
- Minimum lot and lot step are set by your broker. When the exact value is below the minimum lot, the trade cannot be placed at that risk.