Section A: The Mathematical Anatomy of Forex Margin
In retail foreign exchange, margin is not a fee, transaction cost, or commission. Rather, margin is a good-faith security deposit that a broker sets aside from your account balance to open and maintain a leveraged position. When you initiate a position, the broker temporarily locks that capital as collateral against potential adverse market price movements.
Universal Forex Margin Formulas
When you open a position in EUR/USD, GBP/JPY, or AUD/CAD, the broker always evaluates the base currency (the first currency in the pair). For example, 1 standard lot of EUR/USD is 100,000 EUR. If your account is in USD, the broker converts 100,000 EUR to USD at the prevailing spot rate and divides by your leverage ratio.
