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




Open System Settings



Go to General



Click Storage



Wait for macOS to calculate storage usage



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




Open Terminal



Type:




tmutil listlocalsnapshots /





Find the snapshot dates



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




Connect your iPhone or iPad



Open Finder



Select your device



Click General



Choose Manage Backups



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




Open Finder



Press Command + Shift + G



Enter:




~/Library/Caches/





Delete contents from apps you recognize




Delete System Caches



Steps




Open Finder



Press Command + Shift + G



Enter:




/Library/Caches/





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




Open Safari



Go to Settings



Select Privacy



Click Manage Website Data



Remove unwanted website data




Chrome




Open Chrome



Go to Settings



Select Privacy and Security



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




Open Finder



Search for:




.dmg





Search again for:




.pkg





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




Open Terminal



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




Open System Settings



Go to General



Select Storage



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




Save your work



Restart your Mac



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




Back up your Mac



Erase the drive



Reinstall macOS



Restore only personal files



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




System Data stores caches, backups, temporary files, and AI assets.



Time Machine snapshots are a major storage culprit.



Old iPhone backups can consume huge space.



Browser and app caches grow constantly.



Xcode files often occupy tens of gigabytes.



Apple Intelligence now contributes to System Data growth.



Restarting your Mac can recover storage instantly.



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.