In MetaTrader terminals, the minimum trade amount is determined by the margin required to open a trade. It depends on next factors:

For several instruments, the lowest margin requirement is just 1 USD. For example, to open a trade for such instruments as EURUSD, GBPUSD, AUDUSD, NZDUSD only 1 USD margin is required.

You can also check the minimum trading amounts for each instrument on the CFD Specifications page.

Please note: the company reserves the right to change trading conditions — including the minimum trade amount — at any time and at its sole discretion.