Comparisons & alternatives · Disk-space analysers
Why can't any storage app account for every gigabyte on my Mac?
Short answer: Parts of every Mac's disk are off-limits to all apps, and snapshot-held space belongs to no visible file. Storage Studio says what it couldn't read and shows held space separately instead of guessing.
Because some of the disk is off-limits to every app, by design. macOS protects its own system areas, other user accounts' files aren't readable to you, and space held by your Mac's local snapshots doesn't belong to any file you can see. Every disk tool runs into the same walls; the difference is how honestly it reports them.
Storage Studio's approach:
- the Storage Inspector's footer says how much it covered and what it couldn't read, and says "at least" when a figure is a minimum;
- folders it isn't allowed to read are marked unreadable rather than counted as empty;
- snapshot-held space is shown on its own line, with how old the oldest snapshot is.
Granting Full Disk Access lets it see more of your own data, but no app can see everything. See Mac storage basics.