How many GB does my IPhone 4 have?

So I went to settings - general - about and capacity says 13.7GB and avaliable says 8.4GB. Well that makes no sense cause don't they come in 8, 16, 32, 64? Also it doesn't say on the back of the phone. Help?

Connect your iphone to itunes and go to the tab where it says the name of your iphone and you will see someting titles GENERAL and click on it and it will give you the info of ur iphone

Its a 16gb.2.3 is for the ios and apps.music take up the rest.

More than likely you have a 16GB iphone. The operating system takes up a few gbs of storage right off the top plus ur apps, contacts, pics and vids.unless you have a LOT of stuff on the phone then its prolly not 32gb