How to use the forex lot size calculator
- Pick your account currency and enter the balance you trade from.
- Choose the risk. Either a percentage of the balance or a fixed amount of money.
- Select the currency pair. The calculator knows each pair's pip size and contract size, and includes gold and silver.
- Enter your stop loss in pips. This is the distance from your entry to the price where the trade is wrong.
- Add a take profit in pips if you want the reward and the reward to risk ratio.
When the pair is not quoted in your account currency, the calculator needs one exchange rate to turn the pip value into your currency. It fills it in from the European Central Bank's latest reference rate, and you can type your broker's own rate over it.
The forex lot size formula
risk amount = account balance × risk percent
pip value = pip size × contract size × quote-to-account rate (per standard lot)
lots = risk amount ÷ (stop loss in pips × pip value per lot)
A standard lot is 100,000 units of the base currency. A pip is 0.0001 for most pairs and 0.01 for pairs quoted in Japanese yen. The pip value is first found in the pair's quote currency, then converted into your account currency. That conversion is why the same stop in pips is worth a different amount on EUR/USD than on EUR/GBP.
Worked example
You trade a $10,000 account, risk 1%, and want to buy EUR/USD with a 50-pip stop and a 100-pip target.
The trade risks $100 to make $200, a ratio of 1 to 2. Those are the numbers the calculator opens with. Change the pair to USD/JPY and the pip value per lot becomes 1,000 yen, about $6.67 when the pair trades at 150, so the same $100 risk buys a larger position.
Standard, mini and micro lots
Lot sizes are a way to name positions of 100,000, 10,000 and 1,000 units of the base currency.
- Standard lot: 1.00 lots, 100,000 units.
- Mini lot: 0.10 lots, 10,000 units.
- Micro lot: 0.01 lots, 1,000 units.
Most brokers let you trade in steps of 0.01 lots, so the calculator rounds down to two decimals and splits the answer into standard, mini and micro lots to make it easy to enter. Rounding down means the real risk is at or below the amount you chose, and the result shows the exact figure.
Choosing a stop loss in pips
The stop is the input that changes the answer most. A 25-pip stop allows a position twice as large as a 50-pip stop for the same risk, and the chart on this page shows the whole curve. Place the stop where your idea is invalidated, such as beyond a swing high or low or past a level the price should not return to, and let the lot size follow from it. Choosing the lot size first and fitting a stop to it is how losses end up larger than planned. Read more on the stop loss and on risk per trade.
Common lot size mistakes
- Using the wrong pip value. A pip on a yen pair or on gold is not worth $10 per lot. Always use the value for the pair you trade.
- Forgetting the account currency. If your account is in euros and the pair is quoted in dollars, the pip value needs converting.
- Leaving the spread out of the stop. The spread adds to the distance the price must move against you on a buy. Add it to your stop in pips.
- Sizing from leverage. Leverage sets the margin a position needs, not how much it should risk.
- Rounding up. A 0.23 lot answer is not a 0.25 lot trade.
What the calculator does not know
The pip value moves with the exchange rate, and the rate used here is a daily reference rate, not your broker's live price. Brokers also define the pip of gold, silver and some exotic pairs in different ways, and contract sizes vary by account type. Check the pip value shown in your platform's order window before you trade. Nothing here is investment advice, and leveraged forex trading carries a high risk of loss.
Frequently asked questions
How do I calculate lot size in forex?
Multiply your balance by the risk percentage to find the amount you will risk. Divide it by your stop loss in pips times the pip value of one lot in your account currency. For $10,000, 1% risk and a 50-pip stop on EUR/USD, the lot size is $100 ÷ (50 × $10) = 0.20 lots.
What is a standard lot in forex?
A standard lot is 100,000 units of the base currency, so one lot of EUR/USD is 100,000 euros. A mini lot is 10,000 units and a micro lot is 1,000 units.
How much is one pip worth for one lot?
On a pair quoted in US dollars, such as EUR/USD or GBP/USD, one pip on one standard lot is $10. On other pairs the value depends on the quote currency and its exchange rate. The pip value calculator shows it for any pair.
How much should I risk per trade in forex?
There is no single right figure. Many traders risk between 0.5% and 2% of their account per trade. What matters is that you choose the figure in advance and that you can live through a long losing streak at that size.
Why does my broker show a different lot size?
Brokers round to their own lot step, set their own contract sizes for gold and indices, and use their own exchange rate for the conversion. Enter your broker's rate in the rate field and use the nearest lot step they allow.
Does leverage change the lot size?
No. Leverage changes the margin your broker holds for the position. Your loss at the stop is the lot size times the stop in pips times the pip value, whatever the leverage.
Can I use this for gold and silver?
Yes, XAU/USD and XAG/USD are in the pair list. Gold counts a pip as 0.10 and silver as 0.01, which is the common convention, but some brokers use different pip definitions. Check yours.
Should the spread be part of the stop loss?
For a long trade you buy at the ask and exit at the bid, so the spread works against you from the start. Adding it to the stop in pips gives a more honest risk figure.