iOS image resolution with Tab bar

Does anyone knows what is the size of the view left visible when using Tab Bar navigation ? I want to use a web view within one of the t开发者_StackOverflow社区ab and I'd like to know what should be the size of the HTML page.

NOTE : I won't support Retina Display at first so let's talk about a 320 X 480 base. I think I shoud use like 450 instead of 480, but it's just a guess.

Thanks !

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For those of you who wonder, you can just check in InterfaceBuilder after having put your Tab Bar. It's 411 if you don't use a nav bar on top also.