Forex lot size calculator
Enter how much you are willing to lose and where your stop-loss sits. The calculator returns the largest lot size that keeps the loss within your plan.
By the TradeFather education team · Updated 27 Oct 2026 · Educational content, not financial advice
Lot size (position size) calculator
Target risk $10.00. Lots are rounded down to 0.01 so you never risk more than planned.
Results assume a USD account and 100,000-unit standard lots. Brokers can differ on contract size, spreads and commission, so confirm with your platform's own specification before trading.
- Lot size = (balance × risk %) ÷ (stop pips × pip value per lot).
- The result is rounded down to 0.01 lots so you never exceed your risk.
- A wider stop means a smaller position — the money at risk stays the same.
The position size formula
Risk amount = account balance × risk %. Pip value per lot depends on the pair. Lot size = risk amount ÷ (stop-loss pips × pip value per lot).
Example: $2,000 account, 1% risk ($20), 40-pip stop on GBP/USD ($10 per pip per lot). $20 ÷ (40 × $10) = 0.05 lots.
Lot sizes for a $1,000 account at 1% risk
| Stop-loss | EUR/USD lots | USD/JPY lots (at 150) |
|---|---|---|
| 10 pips | 0.10 | 0.15 |
| 20 pips | 0.05 | 0.07 |
| 30 pips | 0.03 | 0.05 |
| 50 pips | 0.02 | 0.03 |
Getting accurate results
Place the stop where the setup is invalid, then size. Never shrink a stop to fit a bigger lot.
Add the spread to your stop distance on tight-stop trades.
Some brokers or exchange contracts use different lot sizes — Indian USD/INR futures are 1,000 USD per contract.
Frequently asked questions
+What risk percentage should I use?
Many educators suggest 0.5–2% per trade. Smaller is better while learning.
+Why does the calculator round down?
Brokers accept lots in 0.01 steps. Rounding down keeps the loss at or below your target.
+Does this work for gold?
Gold contract specifications vary between brokers, so it isn't included. Use your broker's contract size.