Finding specific things

The disk-space investigation

Updated 2026-07-31 · 4 min read

Storage settings gives categories; this gives answers. One method, works every time.

The method: drill from the top

du -h -d 1 ~ 2>/dev/null | sort -hr | head

Whatever dominates, drill into it:

du -h -d 1 ~/Library 2>/dev/null | sort -hr | head
du -h -d 1 ~/Library/Developer 2>/dev/null | sort -hr | head

Repeat until you reach the actual folder. Three or four levels always gets there. This beats any tool because you end up understanding your own disk, and it never lies about categories.

Include the system side

If home is not the problem:

sudo du -h -d 1 /System/Volumes/Data 2>/dev/null | sort -hr | head

The reliable culprits, ranked

1. Xcode — DerivedData, DeviceSupport, simulators (developers)
2. Photos / media libraries — inside packages
3. iPhone backups — MobileSync
4. Mail — years of attachments
5. Docker — a single huge disk image (~/Library/Containers/com.docker.docker)
6. node_modules across projects
7. Local Time Machine snapshots — the "purgeable" space
8. Downloads — old installers

The measurements that mislead

• Purgeable space — macOS counts reclaimable snapshots as free; a big copy may fail

despite "free" space. tmutil thinlocalsnapshots reclaims it

• APFS clones — duplicated large files count twice logically, once physically
• Evicted iCloud files — counted in size, occupying nothing

When du and Finder disagree, du reflects the disk.

Turn it into a habit

The whole investigation is thirty seconds once you know the drill. Run it before the disk is full, not after — the difference between a tidy-up and an emergency.

Common questions

What is the best way to see what is using disk space on a Mac?

du -h -d 1 from your home folder, drilling into whatever dominates. It gives real folders, not the vague categories Storage settings shows.

Why does Storage settings show a huge System Data category?

It bundles caches, logs, snapshots and the unclassifiable. du in Terminal reveals what it actually is.