unfortunately, this is common nowadays... an iphone with 128GB does not have 128GB for pure user data, but only what is left after iOS and the apps. furthermore, with hard disks, for example, there is the conversion factor between gigabyte and gibibyte (1000 steps with the herd disk, 1024 steps eff. with NTFS).

Normally this is displayed on the manufacturer's website - just scroll to the bottom of the page to the footnote and you will see it in small print

https://www.sony.ch/de...

why are you asking me this ???