Lot size calculator for MetaTrader 5

Lots are your money at risk divided by what one lot loses at the stop. One lot loses the stop distance times the contract size, converted into your account currency. The calculator above rounds the result down to your broker's volume step and shows what you actually risk after rounding.

How the lot calculator works

Point          = 10^−Digits
Pip            = 10 points for 5- and 3-digit prices, otherwise 1 point
Loss of 1 lot  = Stop distance × Contract size ÷ Rate
Lots           = Risk ÷ Loss of 1 lot, cut to a whole volume step

The third line is MetaTrader 5's own profit formula. The MQL5 reference writes forex and CFD profit as (close_price − open_price) × Contract_Size × Lots, counted in the symbol's profit currency.

The rate converts that currency into your account's. Enter it as 1 account currency = ? profit currency. On USDJPY with a dollar account that is the USDJPY price, say 150. On EURUSD with a euro account it is the EURUSD price, say 1.0850. When the two currencies are the same, the rate is 1 and the field is switched off. There are no live rates here: type the current one.

Worked examples

Every row puts 1% of an account of 10,000 at risk, with a volume step of 0.01 lot.

The first row step by step:

1. A pip of EURUSD is 0.0001, so 30 pips are 0.0030 in price.
2. One lot of 100,000 euros loses 0.0030 × 100,000 = $300 at the stop. A pip of one lot is worth $10.
3. Lots: 100 ÷ 300 = 0.3333. Rounded down to the step: 0.33 lot.
4. Risk after rounding: 0.33 × 300 = $99, or 0.99% of the account.

On USDJPY a pip is 0.01, so one lot loses 0.40 × 100,000 = 40,000 yen at a 40-pip stop. At 150 yen to the dollar that is $266.67, and 100 ÷ 266.67 gives 0.375, rounded down to 0.37.

Check the numbers in your broker's specification

The presets are common values, not your broker's. In MetaTrader 5 the Specification window opens from the symbol's menu in Market Watch. It lists the contract size, the digits, the tick size and tick value, the minimal volume, the volume step and the profit currency.

Gold differs the most. The preset uses 100 ounces per lot with two decimals, so one point, $0.01, is worth $1 on a lot. Some brokers quote gold as a 10-ounce or a 1-ounce contract instead. For gold and indices a «pip» has no single meaning, so enter the stop in points.

What the lot size does not include

• Commission, spread and swap. Many accounts charge a commission per lot, and you pay the spread on entry. Swap is charged for holding overnight. None of them are in the result.
• Slippage. A stop that fills at market can fill beyond its price. The risk per trade guide shows a real trade where the loss reached 1.81 times the planned risk.
• Margin. It does not change the risk. For forex, MetaTrader 5's help computes margin from lots, contract size and leverage: 0.33 lot of EURUSD at 1:100 holds 330 euros, at 1:500 66 euros.
• Minimal volume. If the result is below one volume step, the trade cannot be opened at this risk; the calculator says so. The Specification also lists a minimal volume, and it can be larger than the step: check that your lots reach it.

For crypto futures on Binance, Bybit or OKX use the position size calculator. How a MetaTrader 5 account connects to a journal: the MT5 page. A free trading journal template keeps the same numbers by hand.

Frequently asked questions

How much is one pip on 1 lot of EURUSD?

$10: 100,000 × 0.0001. On a mini lot (0.1) it is $1, on a micro lot (0.01) 10 cents.

Pips or points: which does MT5 use?

MetaTrader 5 counts in points, the smallest price step. On 5-digit and 3-digit quotes one pip is 10 points.

Why round the lots down?

The broker accepts a volume only in whole steps. Rounding down keeps the loss within your risk.

What if my account is in another currency?

Enter the rate as 1 account currency = ? profit currency. For a euro account on GBPUSD that is the EURUSD price.

Sources

• MetaTrader 5 user guide, the Market Watch window: what the Specification shows — contract size, digits, tick size and value, minimal volume, volume step, profit currency.
• MQL5 documentation of symbol properties: the Forex and CFD profit formula (close_price − open_price) × Contract_Size × Lots, and the SYMBOL_TRADE_CONTRACT_SIZE, SYMBOL_VOLUME_STEP and SYMBOL_CURRENCY_PROFIT fields.
• MetaTrader 5 user guide on forex margin: volume in lots × contract size ÷ leverage.
• IG glossary entry on the pip: the fourth decimal for most pairs, the second for pairs with the yen.
• CMC Markets on forex lot sizes: 100,000 units in a standard lot, with mini and micro lots below it.
• MQL5 blog post on XAUUSD sizing (2026): gold contracts of 100, 10 or 1 ounce, depending on the broker.