Update from ios 6 to ios 8 I have an iPad 4.  Still have ios 6.  Want apps I can't purchase since they require ios 7.  How much space am I losing to upgrade to current ios 8 version?
You can see below the free space available with iOS 8 for each kind of devices :



Edit :

Table from http://www.techrepublic.com/article/lawsuit-against-apple-for-ios-storage-misrepresentation-get-the-facts/