How much Data do i need & Cost?

[Mista SpongeBAWB]

I check my facebook sometimes, i occasionally download a couple of apps/games (such as angry birds, barcode scanner, etc), i sometimes watch youtube videos for a little bit, i use groove shark (music website) for maybe 20 minutes a day. not only that i surf around google to do my homework every other day. how much memory plan should i use?
I use t-mobile (android Prism) and i have unlimited txt/talk right now, how much extra money should that data plan cost?
i got internet at my house also which may reduce data usage by a slight bit.
i do 30% of the stuff listed about at my house, mostly the downloading apps/Facebook using wifi also.
if so then how do i use the converter?
and how much is it for each of the plan represented?
tmobile's calc seems to be a little exaggerating.
att's calc doesnt seem to be that much lol.

[Blah]

Do you do all of that over wifi? If so, then get the lowest possible.
If you use data for all that then I would get the middle.
Try this if you do everything using cell data(like not wifi)
http://www.t-mobile.com/Tools/MBCalculat...?tab=phone