How to Clean Huge “System” Storage on Mac

Mac “System” taking up too much space in macOS High Sierra or Mojave? here are some free methods to clear the huge “System” storage on your Mac.

Some days ago, I found one Reddit user’s post telling the “System” taking up a huge space on Mac. It was the first time I met the Mac “System” storage problem. And it was described as follow:

Hi Mac Users, System is taking an incredibly large amount of space. I mistakenly loaded heavy video files to Numbers and the hard disk immediately filled up. Any help accorded will be highly appreciated.

After I checked my computer storage usage and I was surprised to find my “System” is also taking an incredibly huge space – 43GB of the total 120GB on my MacBook Air.

My Mac Huge System Storage
My Mac Huge System Storage –  Feb 2018

As well known, the Mac operating system usually takes up from 8GB to 13GB. So I don’t think my Mac “System” storage could be that huge, so I searched to find how it defines  “System” storage for a Mac, and how to free up that storage.

What is in the Mac “System” Storage?

The “System” on your Mac storage bar stands for that space your macOS operating system used, including the system itself and the caches and cookies it generated while driving on your computer hard drive.

Sometimes, your Mac may mistakenly put other sections into the “System” storage. For instance,  my mac made the mistake of failing to exclude the “Music creations” and “iOS files” (iOS backups) from the “System” storage, so that I get a huge “System” on the storage bar. 

And after I clicked the Manage.. button on the top left of the bar, it showed the real system storage was taking only 29.3 GB. And there were two new categories named “iOS files” and “Music creations” being separated.

Correct Storage Usage on My MacBook
Correct Storage Usage on My MacBook – Feb 2018

And the sum of the storage size of these three parts (System, Music Creation, and iOS Files) is 43.38GB, equal to the size of the huge System storage I showed before on the storage bar.

4 Tips to Quickly Clean Storage on Your Mac

On the storage manager page, you’ll have a detailed view of all data types with the size it used. And you can choose any large category to have a clean. And below are some usual and free methods to free up your Mac storage.

  1. Delete useless iOS backup files, applications, and documents.
  2. Transfer media files like photos, video, music, and iBooks to an external disk drive or cloud. And then delete them.
  3. Empty your Trash bin to get more free space.
  4. Remove your iPhone or iPad software updates on your Mac.

Most of these methods aim to remove the larger files on your Mac to quickly free up your Mac storage. And if there is any question, please leave your comment below.

10 thoughts on “How to Clean Huge “System” Storage on Mac”

  1. Something to consider when you are transferring media files to an external disk is that you no longer have a backup. The transferred file is the only copy you have, and if it’s on a single disk, it is prone to loss. Everything you care about needs to be on at least 2 drives.

  2. So how did you reduce the “System” component? I’ve got a 1Tb drive and 857Gb is being used by “System” which I can not for the life of me reduce. I removed and deleted files, moved them to an external drive, deleted apps only to find “System” getting bigger each time… With less than 10gb left I can’t do a thing on my computer….

    1. Hi Frede,

      Me too!!! This is totally weird. Mac used to be logical and intuitive; me thinks that they have gotten a tad bit too cute with their storage systems.

      Good luck to us both!


Leave a Reply

Your email address will not be published. Required fields are marked *