What is “Other” storage on a Mac, and how can I clean it out?
Note: Under MacOS 12 Monterey, the category "Other" has been changed to "System Data" but the following information still applies.
Note 2: If your goal is to free up space to perform a MacOS upgrade, performing the same upgrade via Online Recovery mode (boot with Command-Option-R held) requires less space to be freed up. For example, upgrading a MacBook Air via System Preferences required ~38 GB of free space, upgrading via Online Recovery required only ~27 GB free.
Parkinson’s Law can be generalized to suggest demand always expands to match supply. In terms of your computer’s internal storage, that means at some point, no matter how much available internal storage you selected when you bought your Mac, eventually you may find that your drive is getting full and you need to free up space.
I’ll use one of my Mac notebooks, a 2017 15” MacBook Pro with a 500 GB SSD, as an example (even though I have plenty of storage available). One way to determine what is taking up space on your Mac is to use Apple menu > About this Mac > Storage tab. On this Mac, it shows the following:
The different color bands are categories to which your Mac assigns the files, including Apps, Documents, etc., with bands in different shades of gray used for ‘system’ items such as System (macOS files), Trash, and Other. In this case, of the various categories comprising the 186 GB of space used on the SSD, Other takes up the biggest block, using 88 GB of space as shown after clicking the Manage button:
If I wanted to free up space on this Mac, starting with that biggest chunk seems like the most efficient approach. But what is Other? Essentially, it’s a catch-all category for files on the Mac that are simply not categorized as something specific like Apps, Documents, TV, etc. For the most part, these files are created and saved by various apps on the Mac, mainly in the ~/Library folder. However, when using Apple menu > About this Mac > Storage tab, you cannot access the files in Other directly. You can navigate to ~/Library in Finder by holding the option key and clicking Go menu > Library, but it’s often easier to use a disk management utility to identify the larger files. Personally, I use the free Disk Inventory X; another option is the free OmniDiskSweeper, and there are also apps on the Mac App Store that offer similar features, such as DiskSight and Diskopolis. These apps do not distinguish what is in Other, but they will show everything taking up space on your drive and allow you to sort it by size and to find it, regardless of whether About this Mac > Storage puts it in a specific category or in Other.
On my 2017 15” MBP, for example, Disk Inventory X, shows that the major culprit for using space is Microsoft Outlook data, which is buried several nested folders deep in the ~/Library folder and is using 56.4 GB of space (about 30% of my total disk usage; drilling down further shows that 43.6 GB of that is attachments):
In this case, deleting the files directly in Finder is not the best approach (that is one reason the ~/Library folder requires the extra step of holding down the option key to access it from the Go menu). Rather, I would need to go into Outlook and use that app’s search/sort tools to identify the emails with large attachments and delete the emails, or just the attachments if desired.
The app(s) using large amounts of storage space in Other, and the best way to free up that storage space, will depend on the app(s) installed. Hopefully the above information enables you find the files on your drive that are taking up the most space. You can then free up needed space by deleting those files or moving them to an external drive.
