Incorrect iCloud storage estimate
I am trying to back up my camera roll to iCloud. The only app that is "on" to be backed up is the camera roll. I have 5.0 GB of available storage. My phone says that the camera roll should take up 3.6 GB. However, the "Next Backup Size" is 5.3 GB and the phone is telling me that I need an additional 315 MB to back up the phone. Why? The amount of storage needed is less than the amount of storage available, so it should work. Yet, it's not. Help please.
iPhone 5, iOS 6.1.4