Why is the 64GB SSD formated to 55GB

[fosters2]

I was asked why the 64GB SSD is formated to 55.45 GB. I don't know why the full 64GB is not available.

Any ideas what happened to the 9 GB? Is it possible to recover this space?

 

[Eidorian]

https://forums.macrumors.com/threads/427947/

There's a thread on the exact same topic a few posts down.