For FX, the minimum trading volume is from micro lot (0.01 lot / 1000 currency).
For Index CFD products (i.e. JPN225 and NAS100 etc), the minimum trade volume and volume step is 0.1 lots.
Maximum trading volume is 100 lots per order for FX currency pair and stock index,
You can trade up to 50 lots of metal for one order and 20 lots of crude oil.
For the minimum trading volume and contract size of other transactions, please right-click on the indicative price display of MT4 / MT5 and check the "Specifications" column.