---
id: comparisons.why-no-tool-can-account-for-every-byte
url: https://storagestudio.us/faq/comparisons/why-no-tool-can-account-for-every-byte
category: "Comparisons & alternatives"
subcategory: "Disk-space analysers"
question: "Why can't any storage app account for every gigabyte on my Mac?"
alt_questions:
  - "disk analyzer doesn't add up to used space"
  - "missing gigabytes mac storage app"
  - "why does daisydisk show hidden space"
  - "storage app can't see system data"
  - "unaccounted space 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."
tags: ["system data", "full disk access", "measurement"]
related: ["https://storagestudio.us/faq/comparisons/disk-visualisers-vs-storage-studio", "https://storagestudio.us/faq/comparisons/storage-inspector-vs-about-this-mac-storage-bar"]
applies_to: "all"
last_reviewed: 2026-10-01
---

# Why can't any storage app account for every gigabyte on my Mac?

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](https://storagestudio.us/faq/mac-storage-basics/).