How to free up disk space before a macOS update

A practical guide from the makers of Clear Storage — Disk Visualizer

The macOS installer wants more free space than the update itself occupies — it needs room to download, unpack and stage the whole thing. If the updater says you don't have enough space, here's a 30-minute routine that finds it without touching anything you'd miss.

Minute 0–5: See the map

Run a full scan in Clear Storage and open the visualizer. The treemap shows where the big blocks are; the scan results show the total reclaimable per category with a "found to clean" figure. You now know whether this is a quick sweep or a real excavation.

Minute 5–15: The zero-regret categories

Clear these first — they carry essentially no risk:

1. Downloads installers: old DMG and PKG files. Already installed, purely dead weight, often several GB.
2. Developer caches (if you use Xcode): DerivedData and package caches regenerate on the next build.
3. Empty folders: no space by themselves, but they clear the view for the next steps.

Minute 15–25: The judgment categories

1. Duplicates: keep one copy per group, remove the strays. Sort groups by size and work from the top.
2. Screenshots & recordings: recordings first (biggest), then old screenshots.
3. Similar photos: one keeper per burst.

Minute 25–30: The big-file check

Open Large Files, sorted descending. You usually need only two or three deletions or archive-moves here to cross the installer's threshold. Check the reclaimed total in history — if you've cleared the space the updater asked for plus a margin, you're done.

After the update

Keep roughly 10–20% of the disk free as standing headroom; macOS performs noticeably worse on a nearly full disk. The menu bar usage icon makes the drift visible so the next update doesn't start with the same scramble.