Usually this space is used by the file system itself. Note that some small amount of hidden space (a few GB) may still remain even after scanning as administrator.And in reverse, some other folders will grow in size correspondingly, and restricted files and folders will become visible here and there on your disk. The hidden space should disappear, or become significantly smaller by size. Use the scan as administrator command.This approach is recommended in Apple's official WWDC 2018 video which mentions DaisyDisk as an example (begin at 9:22). DaisyDisk will not read the actual content of your private data, only the metadata (such as name and size). To override your previous choices, you can open >, go to the tab and add DaisyDisk to the “Full Disk Access” list. In case if you deny the access, the size of hidden space will grow by the corresponding amount, while some folders on the map will appear empty. The system shows you the corresponding dialogs and remembers your choices the first time you scan your disk. macOS Mojave or later: You may see a lot of hidden space if you deny DaisyDisk access to your Calendar, Photos, Contacts and other privacy-sensitive folders.Space missing due to file system errors.File system overhead (2-3 GB is normal for the startup disk).System stuff, like Spotlight index, document versions, etc.Home folders of other users on the same Mac, if any.still hidden - the ultimate remainder of unaccounted space, usually consists of:.This item may include some invisible system volumes and the volumes you created yourself. other volumes (covered in a separate article) - sub-volumes within the same physical disk that share its pool of free space (a new feature of APFS).purgeable space (covered in a separate article) - mostly local snapshots of Time Machine, and also swap files, sleep images and other temporary system files.The following items typically contribute to the hidden space: