How many GB do the new operating systems/iphone 6 use up? How many are left over for apps, music, photos, etc in a 16 GB phone? I have an iphone 4. Under storage it says I've used 6.2 GB, and there are 0 bytes available. I have 400 songs on the phone, a couple of hundred photos, maybe 30 or 40 apps, no games or videos or anything too fancy. I'm trying to figure how many GB I would truly need in an iphone 6.