The system data on my MacBook Air M4 takes up 128GB out of 512GB

Hi! I ran into this problem that the system data on my Mac takes up 128GB out of 512GB, although I bought it literally yesterday and didn't even have time to use it properly. MacOS takes up the standard 24GB

MacBook Air 13″, macOS 26.0

Posted on Sep 2, 2025 05:12 AM

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7 replies

Sep 2, 2025 07:15 AM in response to Kotik3232

Kotik3232 wrote:

Hi! I ran into this problem that the system data on my Mac takes up 128GB out of 512GB, although I bought it literally yesterday and didn't even have time to use it properly. MacOS takes up the standard 24GB

That seems like a lot. I have a two-year-old MBP that has only about 68 GB of system data.


Have you transferred data from a previous Mac? Or loaded a Time Machine backup? Are you in the process of syncing anything to iCloud?

Sep 2, 2025 08:55 AM in response to Kotik3232

Kotik3232 wrote:

I don't use iCloud sync and my Mac is new. I switched from Windows and didn't have these issues, so I was wary. Apple support sent me to their website because they don't offer phone support in my country. I don't use Time Machine either

This is site is not Apple Support. This is a user-to-user forum.


Hopefully someone with more knowledge will see the thread and respond. I don't think what you're seeing is normal.

Sep 2, 2025 09:51 AM in response to Kotik3232

System Data is mainly your own data, stored in the hidden Library and ~/Library folders. Examples include Outlook email attachments, local cache files for cloud storage, etc. Worth noting that System Settings > Storage has several categories, but anything that macOS doesn't associate with one is counted as 'System Data'. I also don't find it very reliable.


For example on my work Mac, System Data is 112 GB, about 40 GB of that is Outlook attachments. Applications is reported as 283 GB, but 200 GB of that is allocated local copies of our cloud storage solution, i.e. it's documents (powerpoint files, mostly) that macOS doesn't see that way.


You can use apps like OmniDiskSweeper or Disk Inventory X to view full disk contents by size (you'll have to allow access to various folders/locations on your Mac).

The system data on my MacBook Air M4 takes up 128GB out of 512GB

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