System caches on a Mac are the caches macOS and its background services keep outside your own Library folder. The main ones are /, shared by every user; /, which belongs to macOS; and the private temporary and cache folders macOS makes for each account in /. A few more, such as Rosetta's translation cache, sit elsewhere.
Most of them are small, all of them can be rebuilt, and macOS clears many of them itself: when space runs low, every day for old temporary items, and when you start up in safe mode. Storage settings counts them in System Data.
The one you can reasonably clear by hand is /, with an administrator's password and a restart afterwards. The others are best left to macOS, and safe mode is the supported way to clear the ones that matter.
This post goes through each location: what it holds, how large it gets, who clears it and what's safe. For your own caches in ~/, see our post on deleting Library caches; for browsers and apps, see how to clear cache on a Mac.
What system caches are on a Mac
A cache is data an app or service keeps so it doesn't have to fetch or work it out again. "System" caches are the ones that belong to macOS, to services running for every user, or to the Mac as a whole, rather than to the apps you open yourself.
How are system caches different from your own caches?
Your own caches live in your home folder and belong to you. You can move them to the Trash in Finder without a password, and apps rebuild them. System caches belong to macOS or to an administrator account, so changing them needs a password, and some can't be changed at all.
They also follow different rules. Some are cleared on a schedule, some only in safe mode, and some never, except by the service that made them.
| Location | Whose it is | What's in it | Who clears it | Level |
|---|---|---|---|---|
~/Library/Caches | Your apps and services | Downloads, previews, app data that can be rebuilt | You, or each app | Safe |
/Library/Caches | Every user's services and helpers | Icons, color profiles, shared app caches | You, with an administrator password | Usually safe |
/System/Library/Caches | macOS | Kernel and extension caches, system data | macOS, and safe mode | Managed by macOS |
/private/var/folders | macOS, per account | Temporary items and caches for each user | macOS, daily and in safe mode | Managed by macOS |
/private/tmp | Every user and tool | Short-lived files | macOS, daily | Managed by macOS |
/private/var/db/oah | Rosetta | Translated Intel code | macOS | Managed by macOS |
Where do system caches show up in Storage settings?
In System Data. Apple describes System Data in System Settings › General › Storage as logs, caches, virtual memory files, temporary files, fonts, app support files and plug-ins, and says you can't manage its contents there.
Some parts of macOS that look like caches, such as downloaded system components and Apple Intelligence's models, count under macOS instead. The System Data guide explains what else sits in that one figure.
Why can't Finder show all of them?
Because many belong to macOS or to other accounts, and Finder can only open folders you have permission to read. You can browse / and your own account's folder in /, but folders owned by macOS's services won't open.
That also means sizes you add up in Finder come up short. Storage settings counts what macOS can measure, so its System Data figure includes caches no folder view will show you.
How big do system caches get?
Usually a few gigabytes in all, far less than your own caches. The exception is /, which can grow large when an app keeps a big cache there or leaves temporary files behind.
- Your app caches, in ~/Library/Caches2–30 GB · Safe
- Shared caches, in /Library/Caches1–10 GB · Usually safe
- Per-user temporary folders1–70 GB · Managed by macOS
- Rosetta translation cache1–10 GB · Managed by macOS
Typical ranges on Macs that have these at all, from the research behind the app's catalog. The top of the per-user range is rare and usually one app's doing; Rosetta's cache exists only on Macs with Apple silicon that run Intel software.
/Library/Caches: caches for every user
The Library folder at the top of your disk has its own Caches folder. Apps, helper tools and macOS services that work for every account on the Mac keep cached data there, instead of in one person's Library folder.
What's inside it?
On a Mac with macOS 27, it holds folders such as com.apple.iconservices.store, the icon cache Finder and the Dock draw from, plus ColorSync and Desktop Pictures. Apple's machine learning services keep folders there too, some of which macOS won't let you open at all.
Third-party apps add folders when they install helper tools or services that run for every user. Those are the ones most likely to outlive the app that made them.
Is it safe to clear /Library/Caches?
Mostly, with care. The catalog rates it Usually safe: like other caches, what's inside can be regenerated, but most items belong to the system or an administrator. Moving them needs an administrator's password, and a service using its cache may only rebuild it properly after a restart.
Never move the Caches folder itself. Move only folders inside it, and only ones you can name.
Which folders are worth clearing?
Three kinds:
- Folders of apps you've removed. Their helpers are gone, so nothing will use or rebuild them.
- One folder that has grown far beyond the rest. Many gigabytes from one helper is worth a look.
- Caches of a third-party service that misbehaves, when its developer suggests clearing them.
Apple's own folders, whose names start with com.apple, are the ones to leave unless you have a specific reason. They're usually small, and the services that use them are often running.
How do you clear it in Finder?
- Quit the apps whose caches you plan to remove.
- In Finder, choose Go › Go to Folder, type
/and press Return.Library/ Caches - Choose View › as List, then View › Show View Options, select Calculate all sizes, and sort by Size.
- Move the folders you chose to the Trash, and enter an administrator's name and password when Finder asks.
- Restart your Mac, check your apps work, then empty the Trash.
The same steps for your own Caches folder, with more on choosing folders, are in our post on deleting Library caches, linked at the top.
What if a helper keeps filling it?
If one folder comes back as large as before within days, the helper that made it is still running. Remove the app with its own uninstaller if it has one, then open System Settings › General › Login Items & Extensions and turn off anything under App Background Activity that belongs to it.
Once nothing uses the folder, it stays gone. Clearing it again while the helper runs only gives it the same work to do.
/System/Library/Caches: macOS's own
The System folder belongs to macOS. Its Caches folder holds data macOS works out for itself, and you don't need to clear it.
What's inside it?
On a Mac with macOS 27, it holds folders for the kernel cache and kernel extension caches, a cache of international data, and a few small files system services use. Some folders inside are readable only by the system.
It's small. On the Mac we checked, everything we could read in it came to well under a megabyte.
Can you clear /System/Library/Caches?
Not by hand, and there's no reason to. Everything in it belongs to macOS, which rebuilds what it needs. The app's list of places it never touches includes the whole System folder, and so should yours.
When these caches do need clearing, safe mode does it. Apple says starting up in safe mode clears some system caches, including font caches and the kernel cache, which are created again as needed.
/private/var/folders: every account's private folders
This is the system cache location that most often grows large, and the one with the strangest names. macOS gives each account on your Mac its own private folder here, under two levels of random-looking names, such as 35 and a long string of letters and numbers.
What are the 0, C and T folders?
Inside each account's folder are a few short-named folders, and macOS's own manual describes three of them:
- 0 is the account's general folder. Others on the Mac can see what's in it, so apps aren't meant to keep anything private there.
- T holds temporary items. The manual says the system may remove files there that haven't been accessed in three days.
- C holds caches. The manual says the system doesn't clean it automatically, and that files there are removed during safe boot.
There's also a folder named zz at the top. Its folders belong to the accounts macOS's own services run as, such as the window server and Spotlight, not to any person.
| Folder | What it's for | When it's cleared |
|---|---|---|
…/0 | Shared, readable files for one account | Not on a schedule |
…/T | Temporary items for one account | Items unused for three days |
…/C | Caches for one account | In safe mode, or by the app that made them |
…/X | Code-signing clones of some apps | When the app quits |
zz/… | macOS's own service accounts | By macOS |
What's in the C folder?
Folders named after the apps and services that use them. On the Mac we checked, the largest were the module cache of clang, the compiler Xcode uses, and com.apple.metal, where Metal, Apple's graphics framework, caches shaders compiled for that Mac's GPU. Folders for fonts, Quick Look previews, the Dock's icons and browser helpers came next.
All of it is rebuilt when it's missing. The cost is time: an app compiles its shaders again, Quick Look makes previews again, and a developer's next build is slower.
What is the X folder, and why does it look so large?
On Macs with Chrome or another browser built on Chromium, you may find folders there ending in code_sign_clone, each the size of the browser. On the Mac we checked, three browsers' folders added up to about 2.6 GB.
They take far less than that. Chromium's own source code explains that the browser makes an APFS clone of itself when it starts, so the files it's running stay available after an update is staged, and deletes the clone when it quits. A clone shares the original's space, so in the usual case it takes almost no extra room.
Why can /private/var/folders grow to tens of gigabytes?
Because the C folder isn't cleaned on a schedule, and because some apps keep large working files in T and C. Video, graphics and developer tools are the usual sources: render caches, compiled shaders, build caches and files left behind when an app quits halfway through a job.
If it's large on your Mac, open it in Finder to see whose folder has grown, and deal with the app rather than the folder. Many apps have their own setting for where they keep caches, or a command to clear them.
How do you look inside it?
In Finder, choose Go › Go to Folder, type / and press Return. Open the folders until you reach the ones named 0, C and T; only your own account's will open.
Choose View › as List, turn on Calculate all sizes in View › Show View Options, and sort by size. Looking is harmless; it's moving things that isn't.
What about other accounts on the Mac?
Each account has its own folder under /. On a Mac shared by a family, there's one for each person, plus the ones in zz for macOS's services.
You can only open your own. Another person's caches and temporary files are theirs, and their apps clear them the same way yours do.
Is it safe to delete /private/var/folders?
No. The catalog rates it Managed by macOS: leave it to macOS. Apps and services use these folders while they run, and removing files under them can make apps lose work in progress or quit unexpectedly.
Guides that tell you to empty it with a Terminal command are the riskiest advice on this topic. Use safe mode instead, which clears the cache part the supported way.
Temporary folders: /private/tmp and others
macOS also keeps a temporary folder shared by every user and tool, at /, which is also reachable as /. Apps, installers and command-line tools use it for files they need only for a while.
When are temporary files removed?
The catalog's entry says macOS removes items there that haven't been opened or changed for three days, as part of its daily maintenance. An Apple engineer described the same rule on Apple's developer forums, adding that the details can vary between releases.
So / rarely grows by itself. When it does, it's usually one tool writing large files there faster than the three-day rule clears them.
Should you clear /private/tmp yourself?
No. The catalog rates it Managed by macOS. Removing items that are still in use can make the app or tool that created them fail, and macOS clears what's old on its own.
If one tool keeps filling it, look at that tool's settings for its temporary folder, or update it.
Other system-wide caches
A few more folders hold data that can be made again. Some belong to macOS, some to developer tools and updaters that work for every user. They're often listed with caches, and some are large, but most aren't yours to clear by hand.
The Rosetta translation cache
On a Mac with Apple silicon, Rosetta translates apps and tools made for Intel-based Macs the first time they run, and keeps the result in / so they open faster next time. macOS manages the folder, and System Integrity Protection keeps other apps out of it.
It grows only when you use software made for Intel-based Macs. Updating those apps to versions built for Apple silicon is the way to keep it from growing.
Font caches
macOS keeps caches of the fonts installed on your Mac, so apps can list and draw them quickly. Parts of them sit in your account's C folder. Apple says safe mode clears font caches, along with the kernel cache.
If fonts look wrong after installing or removing a lot of them, safe mode is the supported way to clear these caches, and macOS builds them again.
Downloaded parts of macOS
macOS downloads many components after installation: speech and language data, voices, fonts, dictionaries, software update files and Apple Intelligence's models. It keeps them in /, which System Integrity Protection protects, and downloads, updates and removes them as features need them.
They aren't caches in the usual sense: a feature that relies on one stops working until macOS downloads it again. Leave them to macOS.
Software Update's downloads
Software Update keeps information about available updates, and some update downloads, in /. System Integrity Protection protects it. It's usually small, but an update that didn't finish installing can leave files behind; installing pending updates in System Settings › General › Software Update lets macOS remove what it no longer needs.
The simulator cache in /Library/Developer
If you develop with Xcode, CoreSimulator builds a shared cache of system libraries for each simulator runtime you install, in /. It keeps one folder per macOS version and runtime, each can take several gigabytes, and it's built again after macOS updates.
The catalog rates it Managed by macOS: it belongs to your installed runtimes. To make it smaller, remove runtimes you no longer need in Xcode › Settings › Components, and CoreSimulator manages its cache to match.
Updaters that keep a download for every user
Some apps install an updater that works for every account and keeps its downloads in the Library folder at the top of the disk. Google Updater, for Chrome and Google's other apps, keeps the last update package for each app in a crx_cache folder, so the next update can be smaller.
That one is Safe: removing it costs, at most, a full download for the next update of each Google app. It never holds more than one package per app.
Compiler caches in your account's C folder
Developers' Macs keep another kind of system cache in the C folder: the module cache of clang, the compiler Xcode and command-line tools use. It saves the compiler work on later builds, and grows as you build more projects.
It's rebuilt as you build, so it isn't worth clearing by hand. Safe mode clears it with the rest of the C folder, and your next builds take longer.
Is the Spotlight index a cache?
Not quite. It's the index Spotlight searches, kept in a hidden folder at the top of each disk, and macOS updates it as files change. It's normally small, but some people have seen it grow very large when indexing goes wrong.
The supported fix is to rebuild it in Spotlight's settings, never to delete the folder. The catalog's entry for the Spotlight index has the steps.
| Folder | What it holds | What to do |
|---|---|---|
/private/var/db/oah | Rosetta's translations of Intel software | Update apps to Apple silicon versions |
| Font caches | Lists and data for installed fonts | Safe mode, if fonts misbehave |
/System/Library/AssetsV2 | Downloaded parts of macOS | Leave to macOS |
/Library/Updates | Software Update's files | Install pending updates |
.Spotlight-V100 | Spotlight's index | Rebuild it in Spotlight settings |
What macOS clears by itself, and when
You don't have to clear system caches for macOS to keep working. It does it on three occasions, and knowing them saves a lot of unnecessary work.
When space runs low
Apple says that when space is needed, macOS clears caches and logs it knows are safe to delete: temporary database files, interrupted downloads, staged macOS and app updates, Safari's website data and more. That's automatic, with no setting to turn on, in both macOS 27 and macOS 26.
Every day
Items in / that haven't been used for three days are removed, and macOS's manual says items in your account's T folder may be removed on the same three-day rule. That keeps temporary folders from growing without limit, as long as apps don't fill them faster.
In safe mode
Apple says safe mode clears some system caches, including font caches and the kernel cache, and that this can temporarily make more storage space available. macOS's manual adds that files in each account's C folder are removed during safe boot.
That makes safe mode the one supported way to clear the system caches you can't reach in Finder.
What changed between macOS versions?
Apple's guides for macOS 27 Golden Gate and macOS 26 Tahoe give the same list of what macOS clears when space is needed, and the same safe mode steps. Storage settings has been in System Settings › General › Storage since macOS Ventura; before that, it was under About This Mac › Storage.
What does change is what's in the folders. Each macOS release adds and retires services, so the folder names you see in / and the C folder differ from one version to the next.
Does restarting clear system caches?
Not the cache folders themselves: a normal restart leaves C, / and / as they were. It does clear macOS's swap files, which aren't caches but are counted in System Data too, so System Data often looks smaller after a restart.
A restart also matters after you clear /, so services start again with fresh caches.
How to clear system caches safely
Put together, a safe clear of system caches has three parts: safe mode for what macOS manages, Finder for /, and a check afterwards. It's worth doing when you need room for something specific, such as a macOS update, or when an app's caches are misbehaving.
Start up in safe mode once
On a Mac with Apple silicon, choose Apple menu › Shut Down and wait until it's off. Press and hold the power button until Loading startup options appears, select your startup disk, then hold Shift and click Continue in Safe Mode.
On an Intel-based Mac, turn it on or restart it and hold Shift until the login window appears. Either way, Safe Boot appears in the menu bar at the login window. Log in, then choose Apple menu › Restart to leave safe mode.
Then look at /Library/Caches
Back in normal mode, open / as described above and sort by size. If nothing stands out, leave it. If one folder belongs to an app you've removed, or has grown to several gigabytes, move it to the Trash, restart and check your apps.
What should you expect afterwards?
A slower first few minutes. Finder and the Dock may redraw icons, apps compile their graphics shaders again, Quick Look rebuilds previews, and apps made for Intel-based Macs may take longer to open. It settles as the caches fill again.
The space you gain is usually modest and partly temporary. Apple calls the gain from safe mode temporary for that reason.
What if System Data barely goes down?
That's common, because system caches are usually a small part of System Data. Time Machine's local snapshots, swap files, your own caches, app data and developer files often weigh far more.
If you cleared caches and System Data hardly moved, the space is somewhere else. The System Data guide, linked above, lists the usual suspects in the order worth checking.
A worked example
Say your Mac needs about 5 GB more for a macOS update. You start up in safe mode and restart normally: System Data drops by a little over a gigabyte, mostly from caches in your account's C folder and the kernel cache.
In /, sorted by size, you find a 3 GB folder from a video app you uninstalled last year. You move it to the Trash with your administrator password, restart, and empty the Trash. With your own caches and the Trash, that's enough for the update.
The numbers are for illustration. On your Mac, the gain could be smaller or larger, which is why sorting by size first matters.
System caches and your Mac's speed
Does clearing system caches speed up a Mac?
No. Caches exist to make things faster, so clearing them makes the next few minutes slower while macOS and apps rebuild them. Clearing caches frees space; it doesn't make a Mac faster.
Any guide or app that promises a faster Mac from clearing system caches is selling the opposite of what caches do.
Can clearing caches fix problems?
Sometimes, and Apple builds that into safe mode. Apple's advice is that if an issue doesn't happen in safe mode, restart normally; if it doesn't come back, the checks and cache clearing safe mode did may have resolved it.
That's a one-off fix for a specific problem, not maintenance. Clearing caches on a schedule brings back the slow first minutes every time, for nothing. A sensible storage routine leaves safe caches to macOS, which clears them when space is needed.
What not to do with system caches
Don't delete whole cache folders
Never move /, ~/ or / themselves, or everything inside them at once. Services expect these folders to exist, and some files inside are in use.
Don't paste Terminal commands
The most common bad advice on this topic is a command that empties / or the system's Caches folders with administrator rights. Commands that delete can't be undone, and fake cleanup guides are a known way to install malware. Everything in this post works through Finder, safe mode and the apps themselves.
Don't turn off System Integrity Protection
Some guides suggest turning off System Integrity Protection to clear protected folders. Don't. It protects macOS from changes by any app, malware included, and none of the space it protects is worth that risk.
Don't confuse caches with preferences
Your preferences and saved app state aren't caches. Clearing ~/ or saved window state frees almost nothing and resets your apps. Leave them alone.
How the app does it
Wombit shows what's using your storage, explains every item in plain language, and clears it safely: Trash first, undoable and logged. Its System Data page splits that one number into named buckets, macOS's caches among them, and shows how much it couldn't explain.
Every system cache location in this post has a catalog entry, with its sources:
/
Library/ Caches/ * Caches that apps and macOS services keep for every user of this Mac, in the Library folder at the top of your disk.
Usually safe · Moves it to the Trash
/
private/ var/ folders Per-user temporary files and caches
Private temporary folders and caches that macOS creates for each user account, in hidden folders with random names.
Managed by macOS · Explained only: never removed
/
private/ tmp A folder shared by all users where apps, installers and command-line tools put short-lived files.
Managed by macOS · Explained only: never removed
/
private/ var/ db/ oah Translated copies of apps and tools made for Intel-based Macs, which Rosetta keeps so they open faster next time.
Managed by macOS · Explained only: never removed
/
System/ Library/ AssetsV2/ * Parts of macOS downloaded after installation, such as speech and language data, voices, fonts, dictionaries and on-device models.
Managed by macOS · Explained only: never removed
/is Usually safe, so it never starts checked in Cleanup. When you check its items, they appear in the review sheet under Needs an Administrator, because they belong to macOS or another user.Library/ Caches - Those items are moved to your Trash by the helper, with an administrator's name and password, and you put them back from the app's Cleanup History.
/,private/ var/ folders /, Rosetta's cache and macOS's downloaded components are Managed by macOS: explained, with how macOS clears them, and never moved.private/ tmp - Nothing under
/is ever moved: the whole System folder is on the app's list of places it never touches.System
Folders macOS didn't let it read are listed, not skipped, so you can see how much it couldn't measure.
Seeing System Data explained is free. Cleanup, including items that need an administrator, is PRO: one payment of $4.99 with lifetime access. Every Pro tool's review is free to open, so you see what would go and why before you buy.
Frequently asked questions
How do I clear the system cache on a Mac?
Start up in safe mode once, then restart normally: Apple says safe mode clears some system caches, including font caches and the kernel cache, and it also removes the cache folder macOS keeps for your account. For /Library/Caches, open it in Finder with Go to Folder and move only folders you can name to the Trash, with an administrator's password, then restart.
Is it safe to delete /Library/Caches on a Mac?
The folders inside it can be regenerated, but most belong to macOS or an administrator, so they need a password to move and services may only rebuild them after a restart. Never move the Caches folder itself. Clear folders of apps you've removed, or one that has grown very large, and leave Apple's own folders alone.
Can I delete /private/var/folders to free space?
No. It holds the private temporary and cache folders macOS gives each account, and apps use them while they run, so removing files there can make apps lose work or quit. macOS removes old temporary items on its own, and safe mode clears the cache part. If it's very large, find which app's folder has grown and deal with that app.
Does restarting a Mac clear the cache?
A normal restart doesn't empty the cache folders. It clears swap files, which System Data also counts, so System Data often looks smaller afterwards. Safe mode is what clears some system caches, and Apple says the space it frees is temporary.
Will clearing system caches make my Mac faster?
No. Caches exist to save time, so clearing them makes the next few minutes slower while macOS and your apps rebuild them. It frees some space, and it can help with a specific problem, but it isn't maintenance worth repeating.
What's the difference between /Library/Caches and ~/Library/Caches?
~/Library/Caches is in your home folder and holds your own apps' caches, which you can clear without a password. /Library/Caches is in the Library folder at the top of the disk and holds caches for every user of the Mac, which need an administrator's password. /System/Library/Caches belongs to macOS and is left to it.
Why is /private/var/folders so big on my Mac?
Usually because one app keeps a large cache or leaves temporary files there. The cache part isn't cleaned on a schedule, and video, graphics and developer tools can fill it with render caches, compiled shaders and build data. Browser folders ending in code_sign_clone look large but are APFS clones that take little extra space.
Sources
- Use safe mode on your Mac · Apple
- Optimize storage space on your Mac · Apple
- Change Storage settings on Mac · Apple
- When /tmp and $TMPDIR directory are cleaned up in macOS? · Apple Developer Forums
- confstr(3) manual page · Xcode man pages
- code_sign_clone_manager.h · Chromium