Forex lot size calculator
Enter your balance, how much you are willing to lose on the trade and where the stop is. The calculator returns the lot size that keeps the loss at the stop within that limit, rounded down to your lot step.
Result
Fill in the fields to see the result
How it works
Fixed-fraction position sizing works backwards from the loss you accept. You decide how much of the account a single trade may cost, for example 1%, and where the trade is proven wrong, which is your stop loss. The lot size is whatever makes those two numbers meet: if the stop is hit, you lose the amount you chose and no more.
The key link is the pip value per lot. A stop of 50 pips on EUR/USD with a dollar account costs 50 × 10 = 500 dollars per standard lot. If you are willing to lose 100 dollars, you can trade 100 ÷ 500 = 0.20 lots. A wider stop means a smaller position for the same risk, and a tighter stop allows a bigger one.
You can enter the stop as a number of pips or as entry and stop prices; the calculator converts prices to pips using the pip size of the instrument. For pairs quoted in your account currency, no other input is needed. For yen pairs on a dollar account, the entry price is used to convert yen into dollars. If your account currency is not part of the pair, enter one exchange rate between the quote currency and your account currency.
The result is rounded down to your broker’s lot step, usually 0.01, so the real risk is never above your limit. The calculator shows the exact figure, the rounded lot size and the risk at that size. If even the smallest step would lose more than you allow, it tells you so instead of rounding up.
Real losses can be larger than the planned risk. Spreads widen, stops can slip in fast markets, and prices can gap over the weekend. Commissions and swaps are not included. Treat the result as the maximum size for the risk you set, not as a recommendation to trade.
Formula
- Money at risk = balance × risk % (or a fixed amount)
- Stop in pips = |entry − stop| ÷ pip size
- Pip value per lot = pip size × contract size, converted to the account currency
- Lot size = money at risk ÷ (stop in pips × pip value per lot)
- Rounded down to the lot step; units = lots × contract size
Example
Balance 10,000 USD, risk 1%, USD/JPY at 150.00 with a 30-pip stop: the risk is 100 USD, one pip on a standard lot is 1,000 yen or 6.67 USD, a 30-pip stop costs 200 USD per lot, so the lot size is 100 ÷ 200 = 0.50 lots (50,000 units).
FAQ
How do I calculate lot size in forex?
Divide the amount you are willing to lose by the stop loss in pips multiplied by the pip value of one lot. Round the result down to the lot step your broker allows.
How much should I risk per trade?
That depends on your strategy and how large a drawdown you can accept. Many traders use a small fixed percentage, but the calculator does not recommend a figure; it works with any value you enter.
Why is my lot size 0?
Because even the smallest lot step would lose more than your risk at this stop. Move the stop closer, accept a larger risk, or skip the trade.
Should I enter the stop in pips or prices?
Either. Prices are converted to pips with the pip size of the instrument. Check the pip size for gold and silver, because brokers define it differently.
Does leverage change the lot size?
No. The lot size here depends only on the risk and the stop. Leverage decides how much margin the position needs; check it with the forex margin calculator.
How is this different from the position size calculator?
The position size calculator works with shares and coins and a price-based stop. This one works in lots and pips and converts between currencies, which is what forex and CFD platforms use.
Are spread and commission included?
No. Add a few pips to the stop if you want the spread included, and keep commission and swap in mind separately.
Other calculators
Calculations only, not investment advice. Check fees, margin rates and contract specs with your broker or exchange.