Q: Hard drive space does not add up

   Re-index Macintosh HD.

   Spotlight reindexing will take a while to finish.

   System Preferences > Spotlight > Privacy

   http://support.apple.com/kb/ht2409

   If you don’t have Macintosh HD icon on the Desktop:

   Finder > Preferences > Sidebar

   Enable Hard disks under “Devices”.

   About “Other”:

   http://support.apple.com/en-us/HT202867

   Try OmniDiskSweeper. This will give the storage size details of the items.

      https://www.omnigroup.com/more

   Select Macintosh HD and click  “Sweep Selected Drive” at the bottom.

   Delete the files yo don’t want to keep.

   Be careful. Delete only the files that can be safely be deleted.