5S capacity incorrect

[Zoola]

I have a 16GB model for just a month and it told me yesterday that my storage is full. Wondering how that could be I opened the menu for storage and added up all the mb's from the app, including photos & videos etc. I found interesting results:

My calculator = 7997MB
My Handy = 11,2 GB
& available = < 1GB
storage max. = 16GB

I know the OS takes a little more Space, that would explain the 4GB gap between max. And used storage. But now there's another in my opinion unexplained gap between nearly 8gb of my calculation and 11,2GB of the handy calculation.
Do you know what's going on here, where the hidden gigabytes used for?

 

[sonicrobby]

Well "16GB" is not actually 16GB to begin with. There are rounding errors and its actually less than 16 (though it shouldnt be 5GB less). My 128GB phone for example only has 114GB of usable space, thats a whopping 14GB that were falsely advertised.

 

[Zoola]

14Gb from 128GB are more than 10% and that's clearly in no tolerance, unacceptable in my eyes, didn't you ask for some refund?