Free space on iOS devices

[Commodore]

What's the "proper" amount of available storage space on "empty" devices with iOS 8? I understand it's a bit less than with iOS 7.
On my iPad mini retina 32 GB, Settings app (or 3rd party system apps) displays 26.34 GB.
On my iPhone 4S 64 GB, it shows 56.58 GB.
(I vaguely remember these numbers used to be somewhere above 27 GB and above 57 GB before.)

 

[twerppoet]

I don't know for sure, but I've seen at least one post that said they lost about 1 GB with the upgrade. That seems a bit high to me, but then again iOS 8 added a lot of features. Far more than a casual look through implies.