If your Mac is low on storage it can cause problems – you might see a message that your start-up disk is almost full, for example, and if you ignore that you might find you can’t even start up your Mac! Low storage can also slow your Mac right down and cause other issues stopping it from running at its best. You may also find that you can’t install an update to macOS if you don’t have enough free storage.
If you are struggling with not enough storage on your Mac you might be wondering what you can delete. Apple offers ways to make this process easy (read how to make more space on your Mac). If you click on the Apple logo > About This Mac and choose Storage you may see a diagram like this one:
This graph indicates how much of your storage is attributed to certain types of files on your Mac. As you can see from the image above: System was using up 19.63GB on our Mac. We’ve heard of people with much much more space being attributed to System though.
Note that in some versions of macOS the types of data are labelled differently. For example, prior to macOS Monterey a large amount of space may have been attributed to Other (we discuss how to delete Other storage on Mac in a separate article). Similarly, rather than System or System Data, you may see a section of storage labelled as macOS (if you don’t see this at first come back after a few minutes and it will be there).
Whether it’s referred to as System, System Storage, macOS, or something else, you can reduce the amount of space taken up by this section of storage. Follow the steps below to free up some space on your Mac.
Find hidden junk and free up the unseen “System” storage. Locate large old folders, background apps, and heavy memory consumers. Use CleanMyMac X to free up space on your Mac and tune it for maximum speed. The new version effectively blocks adware, browser pop-ups, and virus extensions.
System, System Data, or macOS is something of a catch-all title for various elements that are spread across your Mac’s drive. Essentially these are all the same thing: files that don’t fall into the other categories, usually data and files used by macOS, caches, temporary files, backups, plug-ins and so on.
It’s also the operating system files, which you obviously can’t delete. But there are aspects you can delete including: old Time Machine snapshots, iOS backups, cache files, any downloaded disc images for upgrading apps or macOS, and, if you’ve enabled the FileVault encryption feature, files associated with that.
To get an idea of the space being used by System or macOS files, take the following steps:
Click on the Apple logo in the upper left corner of the screen
Select About this Mac.
On the small window that appears, click the Storage tab
You’ll see a graphic illustrating how the space on your disk is being allocated. System is grey and if you hover the mouse cursor over the area it will reveal the size. For a more detailed breakdown, click the Manage… button, which opens a new window with the various elements listed, along with the storage space they’re using.
You’ll see System at the bottom of the left hand column, but, unlike the rest of the list, clicking on it will not reveal which files are being attributed to System. This means you’re on your own when it comes to clearing it out. (You may not see System here in newer versions of macOS).
In Monterey or later rather than System you will see a grayed out macOS listed here.
Why is System storage on my Mac so high?
It all depends on which files are on your Mac. If you have a lot of Time Machine snapshots or iOS backups, then these can often be the cause of a large build up in System.
When you fire up the Storage over view in About This Mac it’s worth waiting a few minutes before concluding that System is taking up an obscene amount of storage. Apparently it can readjust itself after a few minutes when some things that were attributed to System are relocated to iCloud or elsewhere (although that didn’t happen in our case unfortunately).
Can I delete System storage on my Mac?
There is no Clear System or Delete System button available in macOS, so you’ll have to manage the storage yourself. In the sections below we will explain how to delete each type of System file.
While it’s possible to manually delete the various files included in the System category, we’d recommend that you only do so if you’re confident you know what you’re doing. It’s easy to accidentally delete an important file, only to discover it causes problems later on. If disaster does strike, try some of the tips in
how to recover deleted files on Mac.
Plus, before removing anything at all, we’d suggest running a full backup of your Mac’s storage, just so you can return it to the previous state if any problems arise. Read
how to backup a Mac and
best Mac backup software for more details.
Alternatively the safer option woulc be to use a system clean-up app like MacPaw’s
CleanMyMac X or Nektony’s
MacCleaner Pro. You can find reviews of those tools, along with several more in our roundup of the
best Mac cleaner software and optimisation utilities. These apps can safely delete the files you don’t need so you don’t have to worry about finding and identifying files that are safe to delete.
How to remove Time Machine snapshots on Mac
One of the main culprits for taking up space in System is the local snapshots Time Machine creates each day. You might think that Time Machine backups are only saved to an external disk, but Apple also creates local snapshots on your startup volume. The company says that these snapshots will only be saved if there is plenty of free space and old snapshots will automatically be deleted when new ones are made.
This is great if you accidentally save in correct changes to a document, or delete something you didn’t mean to, but it can take up space on your Mac that you might prefer to have access to.
Luckily there is an easy methods for removing local snapshots from your hard drive. You can simply turn off the Time Machine feature itself, which will remove all of the local snapshots stored on your Mac. There is also a slightly more complicated method using Terminal. We explain both in our step-by-step guide for removing these space-stealing artefacts, so read
how to delete Time Machine backups on Mac to find the easy way to remove them.
How to remove old iOS backups on Mac
Another hogger of System space is old backups of your iPhone or iPad. These can use up unnecessary space on your Mac, so it’s a good idea to clear them out once in a while. Depending on which version of macOS you’re using, here’s how to quickly dispense with them.
macOS Catalina or later
Click on your iPhone in the left-hand menu
Select Manage Backups…
Highlight the ones you no longer need
Click Delete Backup then confirm your choice
macOS Mojave or earlier
Select iTunes (in the top left corner) then Preferences
Choose the Devices tab from the window that appears
Highlight the backups you no longer need
Click Delete backup
How to find the System folder on Mac
That’s taken care of two of the biggest users of System storage on the Mac, what about everything else?
macOS likes to keep the System and Library folder hidden, presumably to prevent users from accidentally moving or deleting essential files. But if you want to access that part of your storage, then it’s possible via a menu option in Finder.
To grant yourself temporary access, use the following steps:
Open a new Finder window
Go to your Home folder (press Command + Shift + H)
Right click and choose Show View Options from the menu
Enable the option to Show Library Folder
How to delete files from System or macOS
After following the steps above you’ll able to open the Library folder and look for the files that you suspect are taking up room on your drive. There are actually multiple ways to make the hidden Library folder visible, read: how to show hidden files on Mac for more details about finding hidden files.
At this stage it is really important to exercise caution and only delete things that you know are superfluous. If you aren’t sure that you should delete something don’t. Our advice is that if you don’t feel comfortable doing this yourself you should use a specialist app to do it for you.
When we wanted to recover storage space when we were attempting to install macOS Big Sur we relied on CleanMyMac X which has a tool for clearing System Junk. CleanMyMac X is $29.95/£29.95 right now if you buy the plan for one Mac. There is also a free trial. Download from developer MacPaw here.
Tech Advisor contributor Martyn has been involved with tech ever since the arrival of his ZX Spectrum back in the early 80s. He covers iOS, Android, Windows and macOS, writing tutorials, buying guides and reviews.