Mismatches with Finder
Sometimes you may find that a folder’s size in DaisyDisk mismatches with Finder’s Get Info figure for the same folder.
There can be several reasons for that:
macOS security restrictions. Starting from macOS Mojave, access to certain privacy-sensitive folders such as Calendar, Photos, Contacts etc. is by default restricted for third-party apps. When you first scan your disk in DaisyDisk, the operating system shows you dialogs asking your permission to access your data, and then remembers your choices. In case if you deny the access, some folders on the map will appear empty or too small, while the size of the hidden space will grow by the corresponding amount.
You can grant DaisyDisk full access to your disk in System Preferences: go to Security & Privacy tab, select the Privacy tab and add DaisyDisk to the “Full Disk Access” list.
Hard links. DaisyDisk counts each hard link only once, while Finder wrongly counts each hard link as another copy of the file.
Examples of folders with many hard links are caches of some Apple apps:
File size and HFS+ compression. DaisyDisk counts files and folders packed using HFS+ compression by their physical size on disk, while Finder wrongly counts sizes of such files as if they haven’t been compressed. (Also note that if you copy a compressed file to another location, it may occupy significantly more disk space, because unlike the original, the copy will not be compressed.)
Examples of folders with HFS+ compression are some Apple apps:
In both cases, DaisyDisk’s numbers are more accurate, because they are based on physical disk space, and are more useful when you need to find files which actually take up more disk space.