How To Free Up Disk Space On Mac

Tips
1

My Mac’s storage is almost full and it’s starting to slow down and glitch during basic tasks. I’ve already deleted obvious large files and emptied the trash, but the system data and other storage still take up a lot of space. I’m worried about removing something important or breaking apps I need for work. What are the safest and most effective ways to free up disk space on a Mac, including any hidden files or tools I should use?

2

Had the same issue on my Mac, system data was eating everything. Here is what helped the most.

  1. Check what is large first
    Go to Apple menu > About This Mac > Storage > Manage.
    Look at Documents, Applications, iOS Files, System Data.
    Sort by size and remove what you know you do not need.

  2. Remove old iOS backups
    Open Finder.
    Press Option and click Go > Library.
    Go to Application Support > MobileSync > Backup.
    Delete old device backups.
    These often take many GB.

  3. Clear app caches and logs
    In Finder, Option + Go > Library.
    Check these folders:
    • Caches
    • Logs
    Sort by size, remove big folders from apps you uninstalled or do not care about.
    Do not touch anything with “com.apple.installer” or system update stuff.

  4. Delete old Time Machine local snapshots
    Open Terminal and run:
    tmutil listlocalsnapshots /
    Then:
    sudo tmutil deletelocalsnapshots
    Do that for the old ones.
    This freed 20+ GB for me once.

  5. Remove old Xcode and dev stuff if you used it
    Xcode eats storage.
    Open Xcode > Settings > Locations > Derived Data > Open in Finder.
    Delete everything in DerivedData.
    Also remove old simulators in Xcode > Settings > Platforms.

  6. Clean iCloud Drive local copies
    If you use Desktop & Documents in iCloud, macOS keeps local copies.
    Go to System Settings > Apple ID > iCloud > iCloud Drive > Options.
    Turn on Optimize Mac Storage.
    Then right click big folders in Finder and choose Remove Download.

  7. Empty Downloads and old installers
    Go to ~/Downloads.
    Sort by size.
    Delete DMG, ZIP, PKG files after you installed the apps.

  8. Reindex Spotlight if storage looks wrong
    Open Terminal:
    sudo mdutil -E /
    Sometimes the System Data number drops after a while once indexing is done.

  9. Worst case, nuke “Other” via fresh install
    If System Data stays huge, it is often years of cruft.
    Make a Time Machine backup, or manual backup.
    Create a bootable installer or use macOS Recovery.
    Erase the drive and reinstall macOS.
    Migrate only your user files, not “Applications & Settings” from Time Machine.
    That stopped my random glitching and cleared like 80 GB.

Do a Time Machine backup before deleting things in Library. One mistake there messes stuff up fast.

3

Couple more angles to try that go beyond what @cacadordeestrelas already covered:

  1. Check for huge “hidden” user folders

    • In Finder, open your home folder.
    • Press Command + Shift + . to show hidden files.
    • Check .Trash (sometimes bugged and not really emptied), .npm, .gradle, .docker, .config, .vscode, etc if you do dev stuff.
    • Some of these grow to tens of GB and never clean themselves.

  2. Look for “orphaned” iMovie / GarageBand content

    • Open iMovie, go to Preferences and remove unused media / render files.
    • GarageBand: open it once, let it finish updating sounds, then in /Library/Application Support/GarageBand and /Library/Audio/Apple Loops delete instrument packs you never use (like world music packs if you only do podcasts). They are massive.
    • Same story with Final Cut Pro if you use it: clear render files and old libraries.

  3. Mail attachments & message junk

    • Apple Mail hoards attachments forever.
    • In Mail: Mailbox > Erase Junk Mail and Erase Deleted Items.
    • Then Mail > Settings > Accounts and set “Download Attachments” to “Recent” or “None” for big accounts.
    • Messages: in Messages settings, set “Keep Messages” to 30 days or 1 year, not “Forever,” then manually delete old big threads with lots of photos/videos.

  4. Clean old user accounts & guest junk

    • System Settings > Users & Groups.
    • If you see old accounts you don’t use, log out of them, then delete them and choose “Delete the home folder.” Those home folders can be huge and just sitting there.
    • Also check /Users in Finder for stray folders from previous installs or migrations.

  5. Virtual machines & containers

    • If you ever installed Parallels, VMware, VirtualBox, Docker, UTM, etc, hunt those images down.
    • VM files and Docker images eat space quietly. A single VM can be 40+ GB easy.
    • Docker: in Terminal
      • docker system df to see usage
      • docker system prune -a to remove unused stuff (careful, it’s pretty aggressive).

  6. Photos & “Optimize Storage” properly

    • If you use Photos with iCloud:
      • Photos > Settings > iCloud > turn on “Optimize Mac Storage.”
    • Then leave the Mac plugged in and idle for a while so it actually offloads local full‑res photos. People turn this on and expect instant results, but it needs time and free CPU.

  7. Look for runaways in “System Data” with a more precise tool

    • Apple’s “System Data” category is vague.
    • I’d actually disagree a bit with nuking the whole system and reinstalling as a first fix. Before that, install something like Disk Inventory X or GrandPerspective.
    • They give a visual map so you can see, for example, one random 60 GB log file or cache that “System Data” hides. Then you surgically delete just that instead of wiping everything.

  8. Browser profiles & downloads caches

    • Chrome / Edge / Brave love bloat.
    • In the browser: clear cached images & files, not just history.
    • Also check ~/Library/Application Support/Google/Chrome (or similar for other browsers). Old profiles and profiles you do not use can be removed.

  9. Disable what keeps re‑filling disk

    • If your disk fills again after cleanup, something is generating junk:
      • A runaway log file: check /var/log and ~/Library/Logs for files growing into GBs.
      • A sync loop: sometimes Dropbox, OneDrive, or Google Drive constantly re‑download stuff. Try pausing or uninstalling one cloud app at a time and see if space stops shrinking.

  10. When you do consider a clean install

  • If everything still looks bloated, I’d only go the erase & reinstall route if:
    • The Mac is several major macOS versions old with a long upgrade history, and
    • “System Data” stays huge even after hunting with a disk visualizer.
  • And when migrating, bring over only Documents / Desktop / Photos library manually, not a full Time Machine restore of “everything,” or you’ll just drag the cruft back.

Also, if your disk is under 15–20% free, macOS will keep feeling laggy even after a clean. Aim to keep at least that much space open, otherwise the system just has no room to breathe.

4

Since @cacadordeestrelas already covered a lot of smart angles and the follow‑up added more deep cuts, here are a few different levers to pull, focusing on “System Data” and slowdowns rather than just “delete more stuff.”

1. Target Time Machine “local snapshots”

This one often bloats “System Data” and is not obvious in Finder.

  1. Open Terminal.
  2. Run:
    tmutil listlocalsnapshots /
  3. If you see a big list, delete them:
    sudo tmutil deletelocalsnapshots <snapshotname>
    or to be more aggressive:
    sudo tmutil thinlocalsnapshots / 999999999999
    This forces macOS to free as much as possible.

If you do not actually use Time Machine, turn it off in System Settings so it stops regenerating snapshots.

2. Check APFS volume layout

Sometimes “System Data” is really space taken by other APFS volumes.

  1. Open Disk Utility.
  2. Click “View” and choose “Show All Devices.”
  3. Look under the main container. You might see:
    • Extra volumes for old macOS installs
    • A forgotten “Data” volume from a previous system
  4. If you recognize a volume that you truly no longer need, back up first, then delete only that volume, not the container.

This is one place I slightly disagree with the “just clean install if it’s too messy” idea. If the container is carved up weirdly, a clean install on top will not fix that fragmentation unless you erase the whole disk, which is overkill if the problem is just an orphaned volume.

3. System-level caches & “Other” chunks

Instead of random poking in Library, use the built-in storage management in a more targeted way:

  1. Apple menu > About This Mac > Storage > Manage.
  2. Ignore the generic suggestions everyone repeats.
  3. Look specifically at:
    • “iOS Files” and “Developer” if you ever used Xcode. Old simulators, archives, and device backups can be huge.
    • “Music, Movies, TV” because those apps hide large cache files, especially if you download content for offline.

Then, inside the actual apps:

  • Xcode:
    • Settings > Locations > Derived Data > click the arrow, then delete everything in that folder.
    • Archives: Window > Organizer > delete old archives.
  • TV / Music: in Preferences, make sure you are not keeping old downloads you already watched or streamed.

4. Logs that survive normal cleaning

You might already know about ~/Library/Logs, but some third-party apps write to odd locations.

Quick scan:

sudo du -h -d 3 /var/log | sort -h | tail
sudo du -h -d 3 ~/Library/Logs | sort -h | tail

If you see a single log in the multi‑GB range (common with misbehaving sync clients or virtualization tools), you can usually delete that file after quitting the related app. If it instantly grows again, you have found the culprit for future bloat and slowdowns and should fix or replace that app.

5. Spotlight and Time Machine interaction

When your disk is nearly full, Spotlight indexing and Time Machine can make the Mac feel like it is dying.

Try temporarily:

  1. Turn off Time Machine backups.
  2. Prevent Spotlight from indexing huge, static folders:
    • System Settings > Siri & Spotlight > Spotlight Privacy.
    • Add folders containing large, rarely changed archives (old project archives, VM folders, etc.).

This does not free space, but it can stop the “glitchy during basic tasks” behavior once you carve back some GBs.

6. When to actually do a nuke & pave

I disagree a bit with postponing a clean install forever. If:

  • “System Data” stays massive
  • Disk analyzers show nothing obvious
  • You have upgraded macOS in place multiple major versions

then a full erase of the disk (not just reinstall over top) followed by:

  • Fresh macOS
  • Manually copying only:
    • Documents
    • Desktop
    • Photos library
    • Any clearly needed project folders

can be the cleanest way to cut off old cruft: forgotten daemons, old kernel extensions, misbehaving launch agents, etc.

Avoid restoring “everything” from Time Machine or you will drag the mess right back.

7. About using a dedicated cleanup tool

You mentioned general cleanup, so if you consider something like “How To Free Up Disk Space On Mac” style utilities:

Pros

  • One place to clear:
    • App leftovers
    • Old logs
    • Browser caches
    • Language packs
  • Less digging through obscure folders
  • Good for non‑technical users who do not want Terminal or manual APFS work

Cons

  • Can be over-aggressive:
    • Risk of removing caches that an app expects
    • Rarely, breaking niche software
  • Often run as background “helper” and can consume CPU / RAM
  • You still need to understand what is filling space, or it refills shortly after

Personally I treat those tools as a convenience layer after I have identified the big offenders. Manual control plus a light, occasional cleanup is safer than running auto-clean daily.

8. Final sanity checks to keep it from refilling

Once you have reclaimed space:

  • Keep at least 15–20% of the disk free as a rule.
  • Watch Activity Monitor > Disk tab. If a process is constantly writing, investigate it before your free space vanishes again.
  • Re-check once a month with a disk visualizer just to make sure no single folder grows out of control.

Between what @cacadordeestrelas already walked through and the APFS / Time Machine / log angle here, you should be able to shrink “System Data” without jumping straight to a full wipe, and only go nuclear if the underlying layout or upgrade history is really beyond salvaging.