What is a lot in forex?

A lot in forex is a standard trade size: 1.00 lot is 100,000 units of the base currency, 0.10 lot (a mini lot) is 10,000 units and 0.01 lot (a micro lot) is 1,000 units. In MT5 every order size is entered in lots, in the Volume field.

The base currency is the first one in the pair, so 1.00 lot of EURUSD is €100,000 and 1.00 lot of USDJPY is $100,000. MetaTrader’s own margin example uses the same size: one lot of EURUSD with a contract size of 100,000 (MT5 help: Forex margin).

Lot sizes in forex: standard, mini and micro

Outside forex, a lot is whatever the broker’s contract says. Gold is commonly 100 troy ounces per lot and silver 5,000 ounces, the same units as the COMEX gold and silver futures contracts. Index CFDs have no standard lot at all: each broker sets its own.

Worked example: what a lot size means in money

The margin line follows MT5’s forex formula, lots × contract size ÷ leverage, converted into the account currency.

Lots in MT5

• New order window (F9, or Tools → New Order): the Volume field is the “order volume in lots” (MT5 help: opening positions).
• Toolbox → Trade (Ctrl+T): the Volume column shows each open position’s size in lots.
• Specification (right-click the symbol in Market Watch): Contract size, Minimal volume, Maximal volume and Volume step for that symbol.

The broker only accepts sizes between its minimum lot size and maximum volume, in whole volume steps.

Common mistake: one lot size for every trade

Trading the same 0.10 lot on every trade means the money at risk changes with the stop. On EURUSD, 0.10 lot loses $15 on a 15-pip stop and $60 on a 60-pip stop. On gold at 100 oz, the same 0.10 lot loses $10 for every $1.00 the price moves against it.

Risk-based sizing works the other way round: it starts from the money you accept to lose, places the stop, and derives the lot from both. How to calculate lot size walks through it, and the position size calculator does the sum for any pair, gold or index.

Lots in automated trading

An Expert Advisor sends every order with a volume in lots. PipWarden works that volume out for each trade from your risk per trade (1% of equity by default), the stop distance and the symbol’s tick value at your broker. It rounds down to the broker’s volume step and caps the result at your maximum lot, 5.00 by default. If the size falls below the broker’s minimum, the trade is skipped and logged rather than enlarged. The other checks are on the features page.