Forex Lot Size Calculator
Find the lot size that keeps a forex trade within your risk limit, based on your stop loss in pips.
Calculation Results
For education only. Not financial advice. Trading involves substantial risk of loss.
Choosing a lot size by feel is the fastest way to blow through your risk limit. This calculator works backwards from your risk: enter your balance, the percentage you will risk, the currency pair and your stop loss in pips, and it returns the lot size that keeps a stop-out at your chosen loss.
The formula
Lot size = Risk amount ÷ (Stop loss in pips × Pip value per lot)
Risk amount is your balance multiplied by your risk percentage. Pip value per lot is about $10 for pairs quoted in USD, such as EUR/USD, when you trade a standard lot of 100,000 units.
Worked example
Balance $10,000, risk 1%, EUR/USD, stop loss 50 pips:
- Risk amount: $100
- Pip value per standard lot: $10
- Lot size = 100 ÷ (50 × 10) = 0.20 lots (20,000 units)
A tighter stop of 25 pips lets you take 0.40 lots for the same $100 risk. A wider stop needs a smaller size. The risk stays the same, and only the size changes.
JPY and USD-base pairs
For pairs where USD is the first currency, such as USD/JPY or USD/CHF, the pip value depends on the current price. At USD/JPY 150, one pip on a standard lot is about $6.67. With a 40-pip stop and $100 risk, the lot size is 100 ÷ (40 × 6.67) = about 0.375 lots. Enter the current price and the calculator handles this for you.
Lot sizes at a glance
| Lot type | Units | Lot size entered in platform |
|---|---|---|
| Standard | 100,000 | 1.00 |
| Mini | 10,000 | 0.10 |
| Micro | 1,000 | 0.01 |
Common mistakes
- Choosing lots first, stop second. Set the stop where your trade idea fails, then size from it.
- Ignoring the broker’s lot step. Round down to the nearest step your broker allows, so the risk never exceeds your limit.
- Forgetting spread. The spread widens your real stop distance, so allow a pip or two.
- Mixing account currencies. This tool assumes a USD account.
FAQ
How many lots should a $1,000 account trade? It depends on your stop distance. With 1% risk ($10) and a 50-pip stop on EUR/USD, that is 0.02 lots. Micro lots exist for exactly this reason.
Is lot size the same as position size? Lot size is the forex unit of position size. The position size calculator covers other instruments as well.
Does the calculator include commission? No. Subtract your expected commission from the risk amount if your broker charges it per lot.
Related tools: Pip Value Calculator · Position Size Calculator · Margin Calculator · All trading tools
Educational use only. Not financial advice. Forex trading carries a high risk of loss.
