First, it is important to distinguish between Base Currency (aka Primary) and Term Currency (aka Secondary or Quote).
|Symbol||Base Currency||Term Currency|
Margin is always denominated in the Base Ccy*
*If your account currency is in a different currency than the Base Currency, then it will be converted to your account currency.
The formula is as follows:
Lots x Contract Size x Margin%,
or, (Lots x Contract Size) / Leverage
You can find all Contract Sizes, by right-clicking on any Symbol through MT4's market watch and then 'Specification'
A window will pop up containing information about the selected symbol:
- If you want to Buy 1 lot on EURUSD with a margin percentage of 0.5%, then it is simply 1 x 100,000 x 0.5%= 500 EUR
- If I want to Buy 100,000 USDJPY with a margin percentage of 0.5%, then it is simply 1 x 100,000 x 0.5% = 500 USD
The final amount though depends on your account’s currency.
If your account currency is in EUR, then in the 1st example you’ll need 500 EUR as a margin, while in the 2nd example, you'll have to convert the 500 USD into EUR.