Free up storage
What Is 'Other' Storage on Mac? (And How to Get Rid of It)
That mysterious 'Other' (or 'System Data') chunk on your Mac storage bar is rarely as cryptic as it looks. Here's what's in it and how to shrink it.
“Other” used to be a category Apple displayed proudly on every Mac’s storage screen, lumping together anything macOS couldn’t easily classify. Starting with macOS Monterey, Apple renamed it to “System Data” — but the underlying mystery is the same. You’ll see a chunk that’s 80GB, sometimes 200GB, with no explanation of what’s in it.
The good news: most of System Data is genuinely reclaimable. The bad news: macOS doesn’t make it easy to clean, and a chunk of what’s in there really is needed by the system. Here’s how to tell the difference.
What “Other” actually contains
When the storage bar shows you “System Data” or “Other,” it’s a grab-bag of everything that doesn’t fit cleanly into Apps, Documents, Music, Photos, or Mail. In practice, that includes:
- Cache files from every app you’ve ever run
- macOS system logs and diagnostic reports
- iOS device backups (if you have an iPhone)
- Time Machine local snapshots
- Mail attachment downloads
- Browser caches and history databases
- Plugin data, font caches, dictionary caches
- Update installer remnants from past macOS upgrades
- Xcode derived data and simulator runtimes
- Sleep image and swap files
- Virtual machine disk images
- Language localization files for apps that ship in 30 languages
- Anything macOS can’t classify — usually disk images, archives, and uncategorized files
Some of that you can safely delete. Some of it you cannot. The trick is knowing which.
The single biggest source: app caches
On a typical Mac, somewhere between 10GB and 60GB of “Other” is just app caches sitting in ~/Library/Caches/. Spotify is famous for this — its cache often exceeds 5GB. Slack regularly hits 2GB. Dropbox, Discord, Microsoft Teams, browsers, and any video editing app contribute heavily.
To check manually, open Finder, hit Cmd+Shift+G, paste ~/Library/Caches/, then click Use Groups Off and sort by Size. The big folders at the top are your low-hanging fruit.
What’s safe to delete: any folder inside ~/Library/Caches/. Apps rebuild their caches as needed. The only side effect is that the next launch might be a few seconds slower while things re-cache.
What’s NOT safe: anything in ~/Library/Application Support/. That’s actual app data — your Slack history, your iMovie projects, your saved game files. Looks similar, completely different purpose.
iOS backups masquerading as System Data
If you’ve ever plugged an iPhone or iPad into your Mac and let it back up, that backup lives in ~/Library/Application Support/MobileSync/Backup/. macOS counts it as “Other” or “System Data” — never as a clearly labeled iOS backup unless you go looking.
A single iPhone backup can be 50-150GB. Most people have multiple, from different devices and different points in time, none of which auto-delete.
To find and delete them:
- Open Finder, plug in your iOS device (or skip this if you don’t have one)
- Click the device in the sidebar → Manage Backups
- Delete any old or unrecognized backups
- Or, in Finder, navigate to
~/Library/Application Support/MobileSync/Backup/directly
Each subfolder there is a separate device backup, named with a long hex string. Check the modification date and folder size. Anything older than your current device is usually safe to delete.
Time Machine local snapshots
This catches almost everyone. Even with no backup drive plugged in, macOS keeps “local snapshots” — APFS snapshots stored on your internal drive that act as a buffer between Time Machine backups. They’re invisible in Finder. They count as System Data.
Open Terminal and run:
tmutil listlocalsnapshots /
If you see a list of dated entries, you’ve got snapshots. To delete them all:
sudo tmutil thinlocalsnapshots / 9999999999 4
The numbers tell macOS to thin aggressively. Expect to free 5-30GB. macOS does eventually thin snapshots automatically when free space gets critical, but it doesn’t have to wait for that — you can force it whenever.
The Mail download trap
If you use Apple Mail, every attachment you’ve ever previewed gets cached locally in ~/Library/Mail/V10/MailData/. (V10 might be V9 or V8 on older macOS — same idea.) On accounts you’ve had for years, this folder casually hits 20GB.
The cleanest fix: open Mail, then Mailbox menu → Rebuild on each mailbox you care about. It’s slow — give it the rest of an hour — but it cleans up orphaned attachments.
A faster but more nuclear option: quit Mail, then delete or move the entire MailData folder. Mail will re-download everything from your IMAP/Exchange server on next launch. Don’t do this if you have any local-only mailboxes — they’ll be gone for good.
Browser caches and database bloat
Browsers cache aggressively. Chrome’s profile folder alone can hit 8GB easily. Safari’s local databases can be huge if you’ve used it for years.
For Chrome: clear via Settings → Privacy and Security → Clear Browsing Data. Or delete ~/Library/Caches/Google/Chrome/ directly.
For Safari: enable the Develop menu (Safari → Settings → Advanced → “Show Develop menu in menu bar”), then Develop → Empty Caches.
For Firefox: Settings → Privacy & Security → scroll to Cookies and Site Data → Clear Data.
What you should leave alone
Some chunks of System Data really are needed by macOS:
/private/var/db/— system databases/System/Library/— core macOS files (you can’t delete these without disabling SIP anyway)~/Library/Keychains/— your saved passwords- The
.DocumentRevisions-V100folder — used by Versions for autosave history ~/Library/Containers(the parent — Caches inside is fine)- Sleep images and swap files (macOS manages these automatically)
A common mistake is following a YouTube guide that says “delete everything in /System/Library/Caches” — don’t. macOS protects most of it with System Integrity Protection, but the parts you can touch are best left alone. The amount you’d reclaim is small compared to the risk.
A rough breakdown of what your “Other” probably is
For a typical Mac that’s been used for a year or two without cleanup, System Data tends to break down roughly like this:
- App caches: 15-40GB
- iOS backups: 0-100GB (highly variable)
- Time Machine snapshots: 5-30GB
- Mail data: 2-20GB
- Browser data: 5-15GB
- Xcode/dev caches (if applicable): 20-60GB
- Logs and miscellaneous: 2-10GB
- Genuinely needed system files: 8-15GB
The first four categories are the easy wins. Together they almost always account for the bulk of what’s bloating your “Other” number.
Verifying you actually shrunk it
After cleanup, the storage bar in System Settings doesn’t always update immediately. macOS recalculates in the background, sometimes taking a few minutes. If you want a real-time check, open Disk Utility, click Macintosh HD, and look at Used vs. Free. That number is accurate the moment you read it.
If your “Other” is still huge after manual cleanup, the most likely culprits are: an iOS backup you missed, a virtual machine disk image, or a runaway log file. Spotlight search by file size (Cmd+F → File Size > 5GB) usually finds the last two.
The unsexy truth about “Other” storage: there’s no single fix. It’s a dozen small fixes, each freeing a few gigabytes. Done manually, it’s an afternoon. Done with a tool that knows where to look, it’s about three minutes — and the math just keeps repeating itself every time the disk fills up again.