When I first bought the Air, iTunes said the Capacity was somewhere between 14-15GB. I don't remember the exact number. (I remember I rounded it to 15GB, so it must have been above 14.4)
However, ever since I updated to iOS 7.1.2, iTunes said the capacity was 12.8GB. I am unable to put anything on my iPad past 12.8GB, even though I know I used to be able to. This is ridiculous, the update somehow took away 2GB of memory from my iPad. When checking the iPad on my computer, it reports the Internal Storage of the iPad as 14.7GB.
Added (1). Update: After upgrading to iOS 8, my iPad only has 11.74GB. I know that iPad software would take up space, but why would these updates take up so many GB? Especially my initial update from 7.1.1 to 7.1.2, how did that take up 2GB, when updating to iOS 8 only took up 1GB?
Read more: I have a 16GB iPad Air. Why does it only have 12.8GB, when the internal storage is 14.7GB?