Max output from one plug is 2.4 Amps, if 1 or 2 devices are plugged in you should see 2.4 Amps or 10 Watts. If you plug in 3 or 4 devices, the 4.8 Amps gets averaged out across all plugs (1.6 or 1.2 Amps respectively). Most, NOT ALL devices will handle 10 Watts without any issue, and most phones will charge faster, but the battery gets a little warmer. Also, just as a note, high apmperage devices may not charge. An iPad needs a minimum of 10 Watts to charge for example, so if you have a phone, external battery, iPod, and iPad all plugged in, the iPad will not show it is changing.