Usb hub and external 2.5" storage

How many amps are needed to power an external drive? I want to attach an usb hub with at least 5 external 2.5" drives (no more than 1TB each, most of them are WD) to my WD TV Live. I need a powered usb hub with a power adapter delivering how many amps?

Not sure on amps but I use http://www.mwave.com.au/product/mbeat-13port-usb20-hub-individual-power-switches-and-adapter-aa00443 and just tunr on what ever drive I want to watch " of course you can’t have more than one drive showing at a time but with 13 ports each with its own on/off button you can have all the drives you like Hope this helps

I answered myself. I bought a 3A 7-ports usb hub from dlink and all my 4 drives are powered. I don’t know why you turn them off, my drives are powered down anyway when I don’t use them and this way they are visible and accessible via home networking. When I want to copy a file to a drive from my computer, I go there, and there’s a small amount of time for the drive to power on, it copies then it power down when finished.