How much space is it really in an 16 GB iphone 6?

They tell you when you buy an iphone 6 that you have 16 GB of space but the phone OS in any system will take space so how much space the IOS 8 in an iphone 6 will take, so please tell me how much left will it take?
please hep me and thank you

A 16 gb should have a close to 13 g. If you need more get the 64 g

Another poster this morning said his had 11Gb free out of the box.