Would an iphone 5 case work for i phone 5s too?

I'm only asking because I want to go get a waterproof case from radioshack but they say its for the i phone 5… They did not say it was for the iphone 5s as well…

I'm guessing its probably a little off, close but not an exact fit.

Size is identical

http://www.phonearena.com/phones/compare/Apple-iPhone-5s,Apple-iPhone-5/phones/7710,7378

It should seeing as they are the same physically, except for the dual LED.

Sure, you can use your iphone5 case on your iphone5s.
They are in the same size.
http://www.icolorcase.com/129-iphone-5-cases
You can see on this website, the case is for both iphone5/5s.
So don't worry about it.
If you still could not confirm that, you can try to buy a new case from this website.