A:Answer Take the listed OUTPUT current (1A, 2A, etc.) and multiply it by the OUTPUT voltage (5V) and you'll get the TOTAL POWER it can supply. IOW, if it provides 2A output current, the total output power is 10 watts (through ONE USB socket).
If you plug MORE THAN ONE ITEM into the adapter (up to 4), take the TOTAL output power, divide it by the number of devices plugged in, and that'll give you the MAXIMUM power available for each device.
If you still have questions, look up "Ohm's Law" on the internet - you'll get a lot of formulae for use. :)
