Currently Being ModeratedMay 4, 2012 5:45 AM (in response to jeffj4AU)
Have not seen direct comparisons of file sizes, but it seems reasonable that it would take a bigger file to fill the screen of an iPad vs an iPhone. If you look at some of the apps, the iPad version of an app is larger...or the iPhone version has the option of 1x or 2x sizing to fill the screen. At the 2x size there is much more pixlation going on indicating it takes more data to fill the screen.
I stick to my iPhone 4 for data over the 3G network, and have unlimited so don't worry about usage, but it doesn't take long to hit the numbers you are seeing.