Why Is System Data So Big on Mac

If your Mac is running out of space, it may be caused by the mysterious System Data, which grows silently, hiding app leftovers, outdated logs, and caches. It consumes much storage space, slowing down your MacBook’s performance. To fix it, we suggest MacKeeper’s Safe Cleanup to detect and remove unnecessary files that contribute to the System Data accumulation.

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Why Is System Data So Big on Mac
Written by   Yana Khodun
Published: July 11, 2025

What is System Data on macOS

Understanding what is meant by the System Data notion is significant, while finding out how to find what's taking up space on Mac.

 

In macOS Ventura and Sonoma, the concept “System Data” involves a wide range of storage categories, which are inconspicuous but quite essential files for the stability and efficient performance of the operating system. In contrast to user-generated files like apps, documents, photos, or media, System Data includes installed low-level files that are important for software functionality.

 

Among the System Data components, we distinguish system caches, temporary files, logs, disk images, and old Time Machine snapshots. These elements accumulate over time, consuming storage space.

Common causes of large System Data on Mac

Have you checked your storage settings and now surprised that your System Data is so big on Mac? Among the key causes of large System Data on Mac are:

  • Temporary files
  • Old backups
  • Unused disk pictures
  • Caches

However, this list can be significantly expanded, so see what our research findings suggest below.

1. Accumulated cache files from apps and system

You probably know that apps on macOS generate temporary cache files, which improve functionality and responsiveness. However, over time, these files take up tens of gigabytes, especially with creative or browser-heavy use. The problem is macOS doesn’t clear caches automatically, as they might become necessary again. As a result, they make your Mac System Data large. Thus, we highly recommend you clear app caches from time to time, as a desired step 1 when you learn how to free up space on Mac.

2. Outdated system and app logs

Logs are the components aimed at storing crash reports, error logs, and diagnostic data generated by macOS and third-party apps. Though these files are helpful for Apple diagnostics, when you need to fix some issues, they aren’t cleared automatically, piling up your Mac’s space. Outdated system and app logs make your macOS System Data huge, staying hidden in invisible folders that are rather complicated to detect manually.

3. Old Time Machine local backups

Don’t forget about Apple’s built-in backup tool—Time Machine, which backs up your Mac automatically to an external drive. Even if your external drive isn’t connected, the operating system still tries to save your data by switching to local snapshots. These files are also stored in hidden categories of your internal drive, which are known as parts of the System Data. Old Time Machine local backups may take up to hundreds of gigabytes. Unfortunately, these files aren’t accessible in the Documents or Apps sections, too.

4. iOS device backups and update files

If you’re trying to find out why your System Data is so high on Mac, maybe your iPhone or iPad is to blame. When you connect other Apple devices to your Mac and decide to back them up via Finder, your Mac saves all the backups automatically. These backups embrace numerous components, like app data, settings, messages, and others, using significant storage on your MacBook.

5. Mail attachments and message storage

Due to Mail’s autosaving function, you can easily find the appropriate content offline via Spotlight. At the same time, these files can consume an extremely large amount of storage space, especially if you’re used to receiving emails with large attachments.

6. Podcast downloads and media files

Another culprit of the System data being so big on your Mac is podcast downloads, offline Apple TV content, and other media files, which accumulate in the System data, as the Mac doesn’t categorize this content clearly. As a rule, downloaded media content sticks around after users’ watching or listening. Don’t you relate here?

7. Unremoved macOS update files

Don’t underestimate leftovers after macOS updates that remain on your laptop after upgrading. Actually, these files are downloaded to facilitate upgrading, so they’re important during installation, but then they become useless, still consuming storage space. Moreover, they’re hidden in restricted categories of the System Data, and you need some effort to find and get rid of them.

8. Disk image mounts and virtual machine files

If you use software like Parallels Desktop or VirtualBox, your Apple laptop saves virtual machine images (.dmg files), which aren’t recognized by macOS like apps or documents, so they’re stored in the System Data. Thus, these files also stay hidden from your attention. Even after deleting Parallels, its virtual machine files remain accumulated.

Impact of huge system data on Mac performance

Huge System Data on Mac consumes much disk space, slowing down the laptop’s performance. It causes crashes, slowdowns, unresponsive apps, and failed updates. Regularly removing unneeded files, you’ll make your Mac run smoothly.

A note from our experts: 

 

If you start searching how to delete system data on Mac in an attempt of fixing the huge System Data issue, chill out and use MacKeeper’s Safe Cleanup. It was created to review even the hidden zones of your Mac and harmlessly remove unneeded files. Our tool also eliminates outdated components, caches, leftovers, system logs, useless downloads—just all the components that consume lots of so valuable storage.

 

Do the following to reduce the System Data using MacKeeper’s Safe Cleanup:

  1. Download and launch the MacKeeper app.
  2. Choose the Safe Cleanup tool from the left menu.
  3. Click the Start Scan button.
  4. When the scan is completed, review the results, select the files you don’t need, and choose the Clean Junk Files option to get rid of them.
To remove unnecessary files and solve the problem of huge System Data on your Mac quickly and easily, download the MacKeeper app from the official site, then launch it, choose the Safe Cleanup tool from the left menu, and click the Start Scan button to activate the searching process.
Step 1. MacKeeper > Safe Cleanup > Start Scan
The next step in removing useless files from your Mac via MacKeeper's Safe Cleanup tool is to wait for the scan to be completed, select the files for deletion, and finally click the Clean Junk Files button.
Step 2. Wait for the results > select the files you want to delete > Clean Junk Files

How to manage and reduce System Data size on Mac

You can reduce the System Data size on your Mac by eliminating system and app caches, removing old downloads, clearing logs, deleting Time Machine local snapshots, and then restarting your Apple laptop.  

 

It’s definitely easier to comprehend how much space does macOS take than to catch up with the System data growth. Still, there are a few easy ways to reduce the System Data size manually:

  1. Delete the system and app caches in Finder.
  2. Clear old log files in Finder.
  3. Remove old files in the Downloads folder.
  4. Empty the Trash bin.
  5. Remove Time Machine local snapshots in Terminal.
  6. Find and delete the folders related to apps you have already deleted.

Conclusion

A huge System Data on your Mac means that your laptop is overloaded with invisible files, like old logs, caches, backups, which accumulate so quickly, eating a lot of storage space. The biggest pain in this issue is that these components are so hard to detect and, as a result, remove them.

 

So, to help you and diminish tons of manual deletion process, we recommend the easy and safe solution to the problem—MacKeeper’s Safe Cleanup. It scans your Mac for all unnecessary files and removes them quickly without risking essential data.

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