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Mac disk space analyzer: how to see where your storage actually went

“Storage almost full” tells you there is a problem. It does not tell you which folder is responsible. A disk space analyzer answers that question — it walks your filesystem, measures every folder, and ranks the results so you can see in seconds that a single directory is holding 60 GB. macOS gives you two ways to do this for free, and a visual scanner does it faster. Here is how each one works.

Updated 2026-08-02 · Written by the CleanerMac team · macOS 13–15 tested

What a disk space analyzer actually does

It recursively walks a directory tree, sums the size of every file, and attributes those totals up the hierarchy so each folder shows the weight of everything beneath it. That single idea is what Finder does not do by default — Finder shows the size of files, not the rolled-up size of folders, which is why browsing manually rarely finds the problem.

The output usually takes one of three forms: a ranked list (largest folders first), a tree you can drill into, or a treemap where rectangle area represents size. All three answer the same question; the ranked list is fastest to read, the treemap is best for spotting one enormous outlier.

Option 1 — Apple's built-in Storage pane

Apple menu → System Settings → General → Storage. You get a coloured bar broken into Applications, Documents, Photos, Music, Mail, iCloud Drive, macOS, Trash and System Data, plus an info button beside several categories.

The Documents section is the useful one. It contains a Large Files list, a Downloads view, and a File Browser that shows your home folder as a size-ranked tree you can drill through. For personal files this is genuinely good and costs nothing.

Its limitation is the grey System Data slice. That category is often the largest on the disk and Apple provides no way to open it. If that is where your space has gone, this tool cannot help — see our System Data storage guide instead.

Option 2 — Terminal, the analyzer you already have

The du command (disk usage) is a complete analyzer with no install required. It sees hidden folders, system directories, everything.

• du -sh ~/* | sort -h — home folder contents, ranked. Start here.
• du -sh ~/Library/* | sort -h — user Library, ranked. This is where the answer usually is.
• du -sh ~/Library/Application\ Support/* | sort -h — per-app data, ranked.
• du -ah ~/Documents | sort -h | tail -20 — the twenty largest individual items in a folder.
• sudo du -sh /* 2>/dev/null — the top level of the whole disk.
• df -h / — the authoritative free-space figure, for sanity-checking before and after.

-s summarises per argument, -h prints human-readable sizes, and sort -h orders those human-readable values correctly. Permission errors on protected paths are normal; add 2>/dev/null to hide them. A full pass over a large home folder takes a couple of minutes because it is reading metadata for every file.

Two things du will not tell you: whether a large folder is safe to delete, and whether its contents are duplicated elsewhere. Those still require judgement.

Option 3 — A visual scanner

Visual analyzers add three things on top of du: speed of comprehension, drill-down without retyping commands, and — in the better ones — an assessment of what each item is. CleanerMac's Disk X-Ray takes this approach: it categorises the disk, lets you open any category down to individual files, and annotates each entry in plain language (cache, installer, not opened since a given date) so you can decide without researching every folder name. It runs entirely on your Mac, nothing is uploaded, and it is a one-time purchase rather than a subscription.

Comparing the approaches

There is no wrong answer here. If you are comfortable in Terminal, du plus df plus tmutil is a complete toolkit and you do not need anything else. The case for a visual tool is time and confidence, not capability.

Reading the results without breaking things

Once you have a ranked list, most Macs show the same handful of names at the top. What they mean:

• ~/Library/Application Support/MobileSync/Backup — iOS and iPadOS device backups. Old ones are safe to delete.
• ~/Library/Caches — app caches. Safe once the app is quit; they regenerate.
• ~/Library/Developer — Xcode derived data, archives and simulators. Largely safe; see Xcode derived data.
• ~/Library/Containers — sandboxed app data including Mail. Do not delete wholesale.
• ~/Pictures/Photos Library.photoslibrary — manage inside Photos, never in Finder.
• ~/Library/Group Containers — shared app data. Leave alone unless you have uninstalled the app.
• A folder that seems too big for its contents — check for APFS snapshots with tmutil listlocalsnapshots /, since deleted blocks held by a snapshot still count. See purgeable space on Mac.

Why the analyzer's total may not match Finder

Three reasons, all normal. First, purgeable space: Finder counts it as available while it is still physically occupied. Second, snapshots: blocks referenced by a snapshot are used but belong to no visible file. Third, permissions: an analyzer running without elevated rights cannot measure directories it cannot read, so its total comes in low. Compare against df -h /, which reports at the volume level and is not affected by any of these.

From analysis to action

Analysis on its own frees nothing. Once you know where the space went, work through the deletions in the order that returns the most for the least risk: snapshots, Trash, old device backups, caches, large forgotten files, then app leftovers. Our step-by-step sequences are in how to free up space on Mac and, if you are already at the warning stage, startup disk full on Mac. For the individual gigabyte-sized offenders, see finding large files on Mac.

And once you have a clean baseline, re-running du -sh ~/* | sort -h once a quarter is the cheapest early warning system there is. Anything that has grown unexpectedly stands out immediately against a total you already know.

See your whole disk in one view

Disk X-Ray maps every folder and explains what is safe to remove.

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