RPi Power Consumption
Varies depending on how busy it is and what peripherals are connected.
Running a GUI and running the GPU will take extra power.
The USB devices and Ethernet connection will take power.
Typically, the Model B+ will use 600mA and upwards (up to a maximum of 2A) depending on what peripherals are connected.
From the Raspberry guys: “Model B owners using networking and high-current USB peripherals will require a supply which can source 700mA. Model A owners with powered USB devices will be able to get away with a much lower current capacity (300mA feels like a reasonable safety margin).”