Where does the storage space go

[BenC2020]

So I got the Samsung S6 32GB. Then the max is only 25GB. I understand the 7 GB is possible taken by the android OS.
So i scan the music folder, which has 15.2GB. Then i select the remain folders and check the properties. it calculated total of 800 something MB. That's the total of 16.2 GB then. But it says I only have 5GB left. 25.2-16.2=9. Where did the other 4GB of space go? I have View hidden folder option on on windows.

 

[gozirra]

Probably /cache, /boot, /recovery, /misc, /data, etc.

 

[jnichols16]

In Settngs => System => Storage you will see a graph that shows how all your memory is being used.