Forex Lot Size Calculator
Enter your account balance, risk tolerance, and stop-loss distance to get the correct position size in lots.
- Risk amount
- 10.00
- Pip value per standard lot
- 10.00
- Position size
- 0.05 lots
Position sizing is the single biggest factor in whether a losing trade is a minor setback or an account-ending mistake. The lot size calculation itself is simple once you have the right inputs: it converts a risk budget (how much of your account you're willing to lose on one trade) and a stop-loss distance (how far price has to move against you before you're out) into a position size that keeps the loss, if it happens, at exactly the amount you planned for.
How the calculation works
The formula is: Position size = Risk amount / (Stop-loss in pips × pip value per standard lot). Risk amount is either a percentage of your account balance (most traders use 0.5–2% per trade) or a fixed dollar figure. Pip value per standard lot depends on the pair's pip size (0.0001 for most pairs, 0.01 for JPY pairs) and, if your account currency differs from the pair's quote currency, the current exchange rate between the two.
A worked example
A $1,000 account risking 1% ($10) on EUR/USD with a 20-pip stop loss: pip value per standard lot is 0.0001 × 100,000 = $10, so position size = $10 / (20 × $10) = 0.05 lots. Trading a larger size than that on the same setup means risking more than 1% if the stop is hit.
This calculator doesn't place trades or connect to your broker — it only does the math, so you can plug the result straight into your MT4/MT5 order ticket.