How to Delete System Data on Mac and Speed Up Your MacBook

If your Mac suddenly starts showing the “Startup Disk Almost Full” warning, there’s a good chance System Data is eating up a huge chunk of storage. On some Macs, especially 256GB models, System Data can quietly grow beyond 100GB, slowing updates, app launches, Spotlight indexing, and even overall performance.

The problem has become more common on recent versions of macOS, including macOS Tahoe, because Macs now store more local AI assets, caches, update files, and app data directly on-device. Apple Intelligence features, offline AI tools, browser caches, old backups, and Xcode files can all contribute to massive System Data usage.

The good news is that you can safely reduce System Data storage if you know what to remove and what to avoid touching. Here’s a complete guide to clearing System Data on Mac and reclaiming storage space safely.

What Is System Data on Mac?

System Data is a storage category in macOS that includes files that do not fit neatly into categories like Apps, Photos, Documents, or Media.

It usually contains:

• System and app caches
• Temporary files
• Local Time Machine snapshots
• iPhone and iPad backups
• macOS update files
• App leftovers
• Browser cache data
• Disk image files (.dmg and .pkg)
• Xcode derived data
• Apple Intelligence and AI-related assets

Apple changed these labels over the years. Older versions of macOS used “Other” or “System,” while newer versions like Monterey, Sequoia, and Tahoe now use “System Data.”

Why Is System Data So Large?

System Data can grow unexpectedly because macOS continuously creates temporary files and caches in the background.

Here are the most common reasons:

• Streaming apps cache music and videos
• Safari and Chrome store website data
• Messages app saves image and video attachments
• Time Machine creates local snapshots
• macOS stores update installers temporarily
• Xcode downloads simulators and developer data
• AI features download large on-device models

Apple Intelligence is now another major factor. Modern macOS versions store local AI models directly on your Mac for privacy and offline processing. These files can take up several gigabytes of storage space.

Is It Safe to Delete System Data on Mac?

Yes, but only certain files.

You should never randomly delete hidden system folders because macOS depends on many of them to boot and function correctly.

Safe files to remove

• Old Time Machine snapshots
• Old iPhone backups
• App caches
• Browser caches
• Temporary files
• Old log files
• .dmg installer files
• Xcode DerivedData
• Unused downloads

Avoid deleting

• Core macOS system files
• Hidden system folders you don’t recognize
• Kernel extensions
• System libraries
• Random files inside /System

Before deleting anything important:

• Back up your Mac
• Empty the Trash
• Restart your Mac first

Method 1: Check Storage Recommendations First

Before touching System Data manually, use Apple’s built-in storage tools.

Steps

1. Open System Settings
2. Go to General
3. Click Storage
4. Wait for macOS to calculate storage usage
5. Review large files, unused apps, and message attachments

What to look for

• Large Downloads files
• Old videos
• Unused applications
• Huge Mail attachments
• Messages media

Tips

• Remove apps you no longer use
• Turn on “Optimize Storage”
• Enable automatic Trash emptying
• Move large files to external drives

Method 2: Delete Time Machine Snapshots

Local Time Machine snapshots can consume tens of gigabytes.

macOS usually removes them automatically, but sometimes they remain for weeks.

Steps

1. Open Terminal
2. Type:

tmutil listlocalsnapshots /

3. Find the snapshot dates
4. Delete a snapshot using:

sudo tmutil deletelocalsnapshots 2026-05-10-120102

Replace the date with your own snapshot timestamp.

Remove multiple snapshots

Use this command:

sudo tmutil thinlocalsnapshots / 10000000000 4

This tells macOS to free roughly 10GB.

Tips

• Keep at least one backup elsewhere
• Restart your Mac afterward
• Disable automatic backups if needed temporarily

Method 3: Remove Old iPhone and iPad Backups

Local iPhone backups can easily consume 20GB to 100GB.

Steps

1. Connect your iPhone or iPad
2. Open Finder
3. Select your device
4. Click General
5. Choose Manage Backups
6. Delete old backups

Tips

• Keep only your latest backup
• Use iCloud backups instead if storage is limited
• Old backups often remain forgotten for years

Method 4: Clear Cache Files

Cache files are one of the biggest reasons System Data grows over time.

Delete User Caches

Steps

1. Open Finder
2. Press Command + Shift + G
3. Enter:

~/Library/Caches/

4. Delete contents from apps you recognize

Delete System Caches

Steps

1. Open Finder
2. Press Command + Shift + G
3. Enter:

/Library/Caches/

4. Carefully remove unnecessary cache files

Tips

• Do not delete the cache folders themselves
• Browsers recreate caches automatically
• Restart your Mac after clearing caches

Method 5: Delete Browser Cache

Browsers quietly store huge amounts of website data.

Safari

1. Open Safari
2. Go to Settings
3. Select Privacy
4. Click Manage Website Data
5. Remove unwanted website data

Chrome

1. Open Chrome
2. Go to Settings
3. Select Privacy and Security
4. Click Clear Browsing Data

Tips

• Clearing browser cache may log you out of sites
• Large streaming websites usually create massive caches

Method 6: Delete DMG and PKG Installer Files

Downloaded installers often stay hidden in Downloads folders for months.

Steps

1. Open Finder
2. Search for:

.dmg

3. Search again for:

.pkg

4. Delete installers you no longer need

Tips

• Some old installers can exceed 10GB
• macOS installers are especially large

Method 7: Remove Xcode Files

If you ever installed Xcode, it may be consuming huge amounts of storage.

Simulator files and build data are common storage hogs.

Steps

1. Open Terminal
2. Enter:

rm -rf ~/Library/Developer/Xcode/DerivedData

Tips

• Safe for developers
• Xcode rebuilds files automatically
• iOS simulators can consume 50GB+ over time

Method 8: Reduce Apple Intelligence Storage

Modern macOS versions now store AI assets locally.

Apple recently made it easier to see how much storage Apple Intelligence uses inside Storage settings.

Steps

1. Open System Settings
2. Go to General
3. Select Storage
4. Review macOS and Apple Intelligence storage usage

Tips

• Disabling Apple Intelligence may reduce future storage growth
• AI apps often create temporary cache files
• Offline transcription and image tools also use hidden storage

Method 9: Restart Your Mac

This sounds simple, but it works surprisingly often.

macOS clears temporary files and resets certain cache systems during reboot.

Steps

1. Save your work
2. Restart your Mac
3. Recheck Storage settings afterward

Tips

• Macs left running for weeks accumulate temporary data
• Restarting can instantly recover several gigabytes

Method 10: Clean Install macOS

If nothing else works, a clean install can completely reset bloated System Data.

Steps

1. Back up your Mac
2. Erase the drive
3. Reinstall macOS
4. Restore only personal files
5. Avoid restoring old system caches

Tips

• This is the last resort
• Do not restore full Time Machine system junk
• Reinstall apps manually for best results

Best Apps to Delete System Data on Mac

Some users prefer cleanup utilities instead of manual deletion.

Popular tools include:

• CleanMyMac
• DaisyDisk
• OnyX
• BuhoCleaner

Tips

• Always review files before deleting
• Avoid aggressive “one-click” cleanup tools
• Free apps are often enough for most users

FAQs

Why is System Data taking over 100GB on Mac?

Large caches, Time Machine snapshots, iPhone backups, Xcode files, and Apple Intelligence assets are common reasons.

Will deleting System Data damage my Mac?

Not if you only remove safe files like caches, old backups, and temporary data.

Does restarting a Mac reduce System Data?

Yes. Restarting clears some temporary caches and unused system files.

Can Apple Intelligence increase System Data?

Yes. Local AI models and AI-generated cache files can consume several gigabytes.

What is the fastest way to free storage on Mac?

Usually:

• Delete old backups
• Remove large downloads
• Clear caches
• Remove unused apps
• Empty Trash

Summary

1. System Data stores caches, backups, temporary files, and AI assets.
2. Time Machine snapshots are a major storage culprit.
3. Old iPhone backups can consume huge space.
4. Browser and app caches grow constantly.
5. Xcode files often occupy tens of gigabytes.
6. Apple Intelligence now contributes to System Data growth.
7. Restarting your Mac can recover storage instantly.
8. Clean installs work best for severe storage problems.

Conclusion

System Data on Mac can quickly spiral out of control, especially on smaller SSDs and newer macOS versions with AI-powered features. The good news is that most storage problems come from removable files like caches, backups, temporary data, and installer leftovers rather than core macOS files.

Start with the safe cleanup methods first, especially old backups, cache files, and Downloads folders. In many cases, users recover 20GB to 100GB without touching anything critical. If your Mac still feels bloated afterward, a clean reinstall of macOS may be the most effective long-term fix.