Contract size
Contract size is often confused with lot size, a term also used for the units in one lot. A position's volume is the number of lots it holds: 1.00, 0.10, 0.01. Contract size is how many units of the underlying one lot contains on a given symbol, and volume × contract size gives the units held. This page covers the per-symbol unit; the lot fractions are covered under lot size.
Contract size is the number of units of the underlying asset (currency, ounces, barrels, coins or index units) that one lot of a symbol represents.
The volume entered on a platform multiplies it: units held = lots × contract size. On CFD and spot forex symbols the broker sets the figure per symbol, and MetaTrader 4 and MetaTrader 5 list it in each symbol's specification. Forex symbols follow the 100,000-unit standard-lot convention, while exchange futures carry a size set by the exchange.
This page covers the mechanic; it is not trading advice.
Why 1.00 lot is not the same amount on every symbol
On MetaTrader 4 and MetaTrader 5 the volume field holds a number of lots, not a quantity of the asset; the platform multiplies that number by the symbol's contract size to find the units traded. A volume of 1.00 lot on EUR/USD is 100,000 euros because forex symbols conventionally carry a contract size of 100,000 units of the base currency, the standard Lot size in forex.
On a CFD symbol the broker sets the size: some markets have a common figure, such as 100 troy ounces on spot gold, and others none. MetaTrader 5 shows it under "Specification" in the Market Watch context menu, described as the number of units of the commodity, currency or financial asset in one lot. A BTC/USD CFD whose specification reads 1 holds 1 bitcoin per lot; on a gold symbol that reads 100, one lot is 100 troy ounces. Neither figure is fixed across brokers, so the same 1.00 lot can hold very different exposure on two symbols, or on one symbol at two brokers.
One lot is not 100,000 units on every symbol, although forex-first material makes it read that way. At the prices worked below, 1.00 lot of EUR/USD is $112,530.00 of exposure, while 1.00 lot of a NAS100 CFD with a contract size of 1 is $29,187.55, about a quarter of that. The specification, not habit, says which of those positions an order opens.
Lots × contract size × price, on three symbols
Notional value, the full market value of a position, is units held × price. MetaTrader 5's margin formula for CFD symbols starts from the same product, lots × contract size × market price, before the broker's margin rate is applied.
Notional value
Notional value = Lots × Contract size × Price- Symbol
- EUR/USD
- Lots
- 1.00
- Contract size
- 100,000 EUR
- Price
- 1.1253
Notional value
$112,530.00
Fractions scale by the same rule: 0.25 lot of the BTC/USD example is 0.25 BTC, or $20,368.00 at 81,472. Had the broker set the NAS100 contract size at 10, an identical 1.00 lot would hold $291,875.50 of notional. Notional drives the Margin held, while the cash value of each price move is covered under Point value.
Exchange futures carry a fixed size
A future's size comes from the exchange's contract specification. CME's WTI crude oil future (CL) is 1,000 barrels, so its $0.01 tick is worth $10 per contract, and its E-mini Nasdaq-100 future (NQ) is $20 times the index. A CFD on either market is a separate contract with the broker, sized by whatever the symbol's specification states.
Related terms
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Common questions
Is contract size the same as lot size?
It depends on which sense of "lot size" is meant. Used for the units in one lot, as in the 100,000-unit standard forex lot, it names the quantity a symbol's specification lists as its contract size. In the sense of volume, the number of lots a position holds (1.00, 0.10, 0.01), it is a different number, and the two multiply: units held = lots × contract size. Forex symbols conventionally use 100,000 units, so 1.00 lot of EUR/USD is 100,000 euros, $112,530.00 at 1.1253. On a NAS100 CFD with a contract size of 1, the same 1.00 lot is one index unit, $29,187.55 at 29,187.55.
Where is a symbol's contract size shown?
In MetaTrader 4 and MetaTrader 5, "Specification" in the Market Watch context menu opens the symbol's settings. They list "Contract size" among the parameters set by the broker, beside the minimal volume and the volume step. A forex symbol such as EUR/USD normally reads 100,000; a CFD symbol reads whatever the broker has set.
Why does a CFD's contract size differ from the futures contract on the same market?
The exchange fixes a future's size: CME's WTI crude oil future (CL) is 1,000 barrels. A CFD is a contract with the broker, which sets each CFD symbol's size itself. On a crude oil CFD whose specification reads 100, one lot is 100 barrels, one tenth of the CL contract.
Does contract size change margin and profit per move?
Yes, on forex and CFD symbols. In MetaTrader 5's forex and CFD calculation modes, profit is the price change × contract size × lots, and margin starts from lots × contract size; its futures modes use the tick value and the initial margin instead. On EUR/USD at 1.1253, 1.00 lot with a contract size of 100,000 moves $10 per pip and, at 1:100 leverage, holds 100,000 ÷ 100 = €1,000 of margin, or $1,125.30. Halve the contract size and both figures halve.