If you don’t have access to a forex margin calculator, here’s the formula for calculating the margin requirement:
Required Margin = (Trade Size x Contract Size x Open Price)/Leverage.
Example: If you buy 1 Lot of EUR/USD at USD1,1800 with a leverage of 100:1, the Required Margin will be: (1 x USD100,00 x USD1,1800) / 100 = USD1,180