Forex lot size calculator
Turn your risk in dollars into the correct lot size (standard, mini or micro) based on your pair, your stop in pips and your capital.
By the TradingCalculator.Pro team · Updated on · About us
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Formula
Lots = Risk($) ÷ (Stop in pips × Pip value)How it works
A lot is a unit of quantity, not of risk. A standard lot is 100,000 units of the base currency; a mini is 10,000; a micro is 1,000. What turns that quantity into money is the pip value, and that depends on the pair, not on your broker.
The maths goes in two steps: first what one pip is worth at the size you will use, then how many of those sizes fit inside your risk. When the pair’s quote currency is your account currency — EUR/USD, GBP/USD and XAU/USD on a dollar account — the pip value is fixed and the sum is direct. When it is not, as in USD/JPY or EUR/GBP, it has to be converted at the current rate, which is why the same stop in pips costs different money on two pairs.
What you get
- Standard, mini and micro lots
- Pip value per currency pair
- Matched to your risk % per trade
Worked example
A $25,000 account risking 0.5% per trade. Long XAU/USD (gold) at $2,380.00 with the stop at $2,371.50.
- Risk in money: $25,000 × 0.5% = $125.
- Distance to the stop: 2,380.00 − 2,371.50 = $8.50 per ounce.
- A standard gold lot is 100 ounces, so the risk per lot is 8.50 × 100 = $850.
- Size = $125 ÷ $850 = 0.147 lots.
Size = 0.14 lots (14 ounces), rounded down to the broker’s 0.01 step.
At 0.14 lots the real risk drops to $119, below the $125 planned. Rounding up to 0.15 would push it to $127.50: overshooting your decided risk on a rounding is free once and expensive two hundred times.
How to use it
- Enter your inputs: the terms of the formula (capital, risk, prices and stop).
- The calculator applies the formula and returns the result in your instrument's units.
- Check the breakdown before trading: anything that cannot be computed is shown empty, never as zero.
Frequently asked questions
What is a pip worth on a standard EUR/USD lot?
$10 per pip on a dollar account, and it is a fixed value. It comes from a pip being 0.0001 of quote and a standard lot being 100,000 units: 0.0001 × 100,000 = $10. On mini lots it is $1 and on micro lots $0.10.
Why does the pip value change on USD/JPY?
Because the dollar is the BASE currency on that pair, not the quote one, so the pip is generated in yen and has to be converted. A pip on USD/JPY is 0.01 of quote, which is ¥1,000 per standard lot; at a 157.00 quote that is $6.37. With the same stop in pips, USD/JPY and EUR/USD do not cost the same.
Standard, mini or micro lots — which should I use?
The one that puts your per-trade risk where you decided it, which is almost never the largest your margin allows. On a $2,000 account at 1% risk you have $20 per trade: with a 30-pip stop that is 0.06 lots, i.e. micro lots. Opening one standard lot there would be risking $300, 15% of the account.
Does the same calculation work for indices and crypto?
Yes, swapping pip value for point value. On the Nasdaq 100 a CFD usually moves $1 per point per contract, so a 90-point stop costs $90 per contract; on BTC/USD the "lot" is usually 1 BTC and the risk per unit is simply the price difference in dollars.
How many lots can I open with $1,000?
The right question is not how many the margin allows, but how many fit inside your risk. With $1,000 at 1% risk you have $10 per trade; with a 25-pip stop on EUR/USD that is 0.04 lots. Margin would let you open 0.27 at 1:30 leverage, and that is precisely the trade not to take.