“Your disk is almost full” is one of the few macOS warnings that gets worse if you ignore it. Apps refuse to update, Photos stops syncing, and eventually you cannot even save a screenshot.
Below are twelve things that actually return space, ordered roughly by how much you get back for the effort. Each one says whether it is reversible.
Before you start, find out where you stand: Apple menu → System Settings → General → Storage.
1. Empty the Trash
Typical: 1–50GB · Not reversible after emptying
Files in the Trash still take up disk. Right-click the Trash icon → Empty Trash. Check Finder → Settings → Advanced → Remove items from the Trash after 30 days while you are there — but only if you are comfortable with things vanishing on a schedule.
2. Delete old iOS and iPad backups
Typical: 8–120GB · Not reversible
If you have ever plugged a phone into this Mac and backed it up, those backups are still here. Open
Finder → your device → Manage Backups, or look in
~/Library/Application Support/MobileSync/Backup. Anything older than your current phone is almost
certainly dead weight.
3. Thin your APFS snapshots
Typical: 5–80GB · Reversible only in the sense that Time Machine can recreate them
Time Machine keeps local snapshots on your internal disk between backups. List them:
tmutil listlocalsnapshots /The safe fix is to connect your backup drive and let a full backup finish — macOS thins snapshots on its own afterwards. This single step frees more space than anything else on a Mac that has not been backed up in a while.
4. Clear developer and AI tool caches
Typical: 10–90GB on a technical Mac · Reversible (everything rebuilds)
The biggest offenders, in order:
# Xcode build artifacts
rm -rf ~/Library/Developer/Xcode/DerivedData
# Homebrew downloads
brew cleanup -s
# Docker images, containers, build cache
docker system prune -a
# npm cache
npm cache clean --forceLocal LLMs deserve their own mention. A single Ollama model can be 40GB, and ollama list will show
you what you have pulled. Most people have three models and use one.
5. Find your largest files
Typical: 5–60GB · Depends what you delete
macOS has this built in: System Settings → General → Storage → Documents → Large Files. Sort by
size. The usual suspects are video exports, virtual machine disks, downloaded course material, and
.dmg installers you never threw away.
6. Clean out Downloads
Typical: 2–40GB · Not reversible
Sort the folder by size, not by date. Most people are carrying several old macOS installers (12GB each) and every disk image they have ever mounted.
7. Uninstall apps properly
Typical: 2–25GB · Not reversible
Dragging an app to the Trash leaves its caches, preferences, application support files and launch agents behind. An app you removed two years ago can still be holding 4GB. This one has enough detail to be its own post.
8. Turn off “Optimize Mac Storage” for Photos — or turn it on
Typical: varies wildly · Reversible
In Photos → Settings → iCloud, “Optimize Mac Storage” keeps full-resolution originals in iCloud and thumbnails locally. If your library is large and you have iCloud space, enabling it can free hundreds of gigabytes. If you want originals locally (and you should, if this Mac is your only copy), leave it off and budget the space.
9. Delete Mail attachments
Typical: 1–20GB · Reversible if the mail is still on the server
Mail caches every attachment you have opened. Mailbox → Erase Junk Mail, and in Mail → Settings → Accounts → Account Information, set “Download Attachments” to Recent or None for IMAP accounts.
10. Find duplicates
Typical: 1–30GB · Not reversible
Duplicate photos, repeated downloads, the same project folder copied “just in case.” Compare by
content, not filename — screenshot.png and screenshot copy.png are the easy case; the same video
under two different names is the one that costs you real space.
11. Clear browser caches
Typical: 1–10GB · Reversible (rebuilds; you may be logged out)
Chrome and Safari both cache aggressively, and a profile that has run for years can hold several gigabytes. Clearing cache is safe; clearing cookies logs you out of everything, so pick carefully in the dialog.
12. Restart
Typical: 1–8GB · Reversible (it comes back)
Swap files, sleep images and various caches get cleared on restart, and macOS runs maintenance routines it defers while you are working. It costs two minutes and is genuinely worth doing before you conclude you are out of options.
What not to do
A short list, because bad advice on this topic is everywhere:
- Do not delete things in
~/Libraryyou cannot name. Real caches and irreplaceable app data sit side by side in there. - Do not disable System Integrity Protection to reclaim space. Nothing you gain is worth it.
- Do not trust a “RAM cleaner.” Free RAM is wasted RAM; macOS is supposed to use it. Freeing memory does not free disk space and does not make your Mac faster.
- Do not run a cleaner that will not show you the list first. If a tool cannot tell you what it is about to remove and why, that is the tool’s problem, not a feature.
Doing this without the Terminal
Everything above is manual on purpose — it all works, and it costs nothing. The trade-off is time, and the risk of deleting something you needed because it looked like junk.
That gap is what Purgy exists to close. It scans the same places this guide points at, then lists every candidate with its size and the reason it was found, sorted into three tiers: junk that rebuilds itself, items worth a look, and your own data, which it locks so it cannot be selected by accident. Anything you approve goes to the Trash, so a wrong call costs you a Finder click.
No subscription, no account, and it never claims to make your Mac faster — because freeing disk space frees disk space, and that is enough.