How to free up disk space on a Mac, ranked by how much it returns

There is no shortage of advice about freeing up space on a Mac. The problem with most of it is that the list is unordered: clearing your browser cache sits next to deleting old iPhone backups as though the two are comparable, when one returns 200 MB and the other returns 40 GB.

This is the same list, ordered by how much it usually gives back. Work down it and stop when you have enough.

First, find out what you are dealing with

df -h /System/Volumes/Data

That is the raw number the filesystem reports. Then open System Settings → General → Storage and compare. If macOS shows meaningfully more free space than df does, the difference is purgeable space and some of the work below is already scheduled to happen on its own.

Note both numbers before you start. Otherwise you will finish with no idea whether any of it worked.

1. Local Time Machine snapshots — often 10-50 GB

This is the big one on most Macs, and almost nobody knows it exists. Even with no backup drive attached, macOS takes hourly snapshots of your disk and keeps them for 24 hours.

tmutil listlocalsnapshots /

Each line is a snapshot. They start free and grow as the files they reference change, so a Mac in heavy use accumulates far more than one in light use.

sudo tmutil thinlocalsnapshots / 50000000000 4

The number is bytes to reclaim, so that asks for about 50 GB. Urgency 4 is the most aggressive setting and tells macOS to delete as many as it needs to.

You lose the ability to roll back to this morning. You do not lose any current file, and you do not affect backups on an external drive. More on how this works.

2. iOS device backups — often 10-40 GB

Every iPhone or iPad you have ever backed up to this Mac left a full copy of itself here:

du -sh ~/Library/Application\ Support/MobileSync/Backup/* 2>/dev/null

Each directory is one backup of one device. If you back up to iCloud now, or if the phone in question was replaced three years ago, that data is doing nothing.

Delete them through Finder → your device → Manage Backups rather than by hand, so the index stays consistent. The full version of this.

3. The Trash — whatever you put there

Obvious, and skipped constantly. Files in the Trash are still on the disk.

du -sh ~/.Trash

Empty it. Also check for a Trash on any external volume you have used, which macOS keeps separately and Finder does not always show you.

4. Downloads — often 5-20 GB

Installers, disk images, and the same PDF four times.

ls -lhS ~/Downloads | head -30

Sorted largest first. Anything ending .dmg or .pkg for software you have already installed is dead weight — the app is in Applications now, and if you ever need the installer again you can download it again.

5. Large files you forgot about — varies wildly

find ~ -type f -size +1G 2>/dev/null | head -40

Video exports, virtual machine images, downloaded datasets, an old disk image of a Mac you no longer own. This is the one where people find the surprise. How to search this properly.

6. Mail attachments — often 5-15 GB

Mail keeps a local copy of every attachment you have received, indefinitely.

du -sh ~/Library/Mail 2>/dev/null

In Mail, Settings → Accounts → Account Information lets you set attachments to download only when opened. Changing that setting does not delete what is already there, but it stops the pile growing.

7. Xcode, if you are a developer — often 20-80 GB

If you have never opened Xcode, skip this. If you have, it is probably your single largest item, ahead of even snapshots.

du -sh ~/Library/Developer/Xcode/DerivedData ~/Library/Developer/Xcode/iOS\ DeviceSupport 2>/dev/null

DerivedData is entirely rebuildable and safe to delete outright. The rest of the Xcode story.

8. Duplicates — usually 2-10 GB

Worth doing, rarely the largest win, and the one most likely to go wrong if you match on filename instead of contents. Do it by checksum.

9. Caches — usually under 2 GB

Last, deliberately. ~/Library/Caches is the first thing most guides tell you to clear and it is almost always the smallest item on this list. Applications rebuild what they need, so it is safe, but you will be signed out of a few things and the next launch of everything will be slower.

du -sh ~/Library/Caches

If that number is not large, leave it alone. When cache clearing is actually the right answer.

What not to touch

• /System — protected by macOS, and attempting to work around that protection breaks updates.
• ~/Library wholesale — it holds application support files, licences and databases as well as caches. Delete inside it selectively or not at all.
• Anything inside a .photoslibrary or .musiclibrary package — the database and the files must stay in step, and editing the package by hand corrupts it. Use the app’s own tools.
• /private/var/vm — swap files. macOS manages these, and deleting them while the system is running achieves nothing.

Check your work

Run the same command you started with:

df -h /System/Volumes/Data

Compare against the number you wrote down. If the difference is disappointing, the space is somewhere this list does not cover, and the way to find it is a disk map rather than more guessing.

Doing it without the terminal

Every step above is a real command and none of them need an app. What they do not give you is the whole picture at once — you are checking nine places one at a time and holding the totals in your head.

CleanSpace runs the same checks in one pass and shows the sizes together, with nothing selected until you select it. The commands above reach the same answer. If you only need to do this once, they are the cheaper route, and they are all in this article.