If your Mac storage is full after an update, most of the difference usually comes from a few predictable things. A snapshot taken before the update holds the old state of your disk. New downloads arrive after it, such as Apple Intelligence's models. And Storage settings needs time to work its numbers out again.
Some of that space comes back by itself within a day or two, as the snapshot ages out and the figures settle. Some of it stays: a newer macOS, and on macOS 27 Golden Gate, Apple Intelligence's models, which download automatically on Macs that support them.
A few things are left behind for you to deal with: a full installer app in Applications, a Relocated Items folder in the Shared folder, and installer files in Downloads. Only the installer app is large. Relocated Items is usually a few kilobytes.
So the first step is to wait a day, restart, and look again before you remove anything. This post goes through each change an update makes, how to tell which one is holding your space, and what's safe to do about it.
What changes on your disk after a macOS update
An update touches several parts of your disk at once. Each one has its own owner and its own timetable, and only some of them stay.
| What changed | Where it is | Goes away by itself? | What to do |
|---|---|---|---|
| Snapshot taken before the update | The startup disk, counted in System Data | Yes, as macOS removes it | Wait, or remove Time Machine's snapshots |
| Apple Intelligence models | Protected system folders, counted under macOS | No | Nothing supported; leave them |
| Spotlight's index, rebuilt | A hidden folder on the disk | It settles once indexing finishes | Leave the Mac on power |
| Relocated Items folder | /Users/Shared | No | Read what's inside, then decide |
| Full installer app | /Applications | No | Delete it if you don't need it |
| Downloaded update files | Protected system folders | Yes, after installing or when space is needed | Leave them to Software Update |
The snapshot and the index are temporary. Apple Intelligence and the newer system are permanent. The leftovers are yours to decide on.
How big can each change be?
Most of these have no fixed size. A snapshot holds whatever changed after it, and the index depends on how much you store. Two have published or measured figures, and they're the ones that stay.
- Apple Intelligence, Apple's figure for most Macs8 GB · Managed by macOS
- Apple Intelligence, Apple's figure for M3 or later with 12 GB memory14 GB · Managed by macOS
- Apple Intelligence on macOS 27, as reported14–30 GB · Managed by macOS
- Full macOS installer app13–20 GB · Usually safe
Apple's figures are its stated maximums for Apple Intelligence. The macOS 27 range is what MacRumors, Ars Technica and owners reported seeing in Storage settings. Installer sizes are typical figures from the research behind the app's catalog.
Why does it look worse in the first hours?
Storage settings works its figures out in the background, and its numbers can jump while it calculates. Apple's guide says System Data varies in size depending on the current state of your Mac, and right after an update that state is busy.
Spotlight indexing, Mail catching up and Apple Intelligence downloading all happen in the same first hours. A reading taken then is a snapshot of a Mac in the middle of settling down.
Do minor updates change as much as major upgrades?
Apple's snapshot applies to any macOS update, and Apple says Spotlight indexes after any software update or upgrade. So a small update follows the same pattern, on a smaller scale.
Major upgrades change more of the disk, so their snapshot tends to hold more, and they're when new features such as Apple Intelligence arrive. Expect the biggest swing after moving to a new version, such as macOS 26 to macOS 27.
Is the space gone for good?
Some of it. A newer macOS is usually a little larger than the one it replaced, and on macOS 27, Apple Intelligence's models stay. The snapshot, the busy indexing and the update files that were staged for the install don't.
Mac storage full after an update: check these first
Before you remove anything, find out which change is holding your space. These checks only read; nothing changes until you decide.
Give it a day, and restart
Leave the Mac on power and online overnight. That lets Spotlight finish indexing, lets Apple Intelligence finish downloading, and gives Time Machine's hourly snapshots time to age out. A restart then clears swap files, which also count in System Data.
Look at Storage settings again
Choose Apple menu › System Settings, click General, then Storage, and wait for the bar to finish calculating. Note the sizes of macOS and System Data, the two categories updates change most.
Neither has a list of files behind it. Apple's guide says you can't select and delete files in either category, so the checks below look at their parts.
Check what macOS includes
Click the information button next to macOS. On a Mac that supports Apple Intelligence, the list includes a line for it, which MacRumors pointed readers to when it reported the larger figures on macOS 27.
If most of the growth is there, it's the newer system and Apple Intelligence, and there's no supported way to shrink either. Look for space elsewhere instead.
Check for snapshots
Open Disk Utility, choose View › Show APFS Snapshots, and select your startup disk's data volume, usually Macintosh HD – Data. Snapshots dated around the update, or Time Machine snapshots older than a day, are what's holding System Data up.
Compare like with like
Finder, Storage settings and Disk Utility each count space differently. Finder counts snapshot space as available, Storage settings puts it in System Data, and Disk Utility's Info window shows it as purgeable.
So compare a figure only with the same figure from before the update. A Finder number against a Storage settings number will always look like something went missing. A simple monthly log of your disk gives you that figure next time.
Check Applications and Downloads
In Finder, open Applications and look for an app named Install macOS followed by a version name. Then open Downloads and look for installer packages and disk images you no longer need. These are the leftovers you can remove yourself.
The snapshot taken before the update
Apple says that in macOS High Sierra 10.13 or later, a snapshot is saved before any macOS update is installed. It's a record of your disk just before the update, kept on the disk itself.
Why does it hold so much space?
A snapshot starts out tiny, then holds on to everything that changes or is deleted after it's taken. An update changes a great deal: apps, caches, indexes and settings, as well as the system itself. Each changed file means the old version stays in use for as long as the snapshot does.
If you also use Time Machine, its hourly snapshots from the same day do the same, for a day each. Storage settings counts all of it in System Data, while Finder counts it as available space. The post on Time Machine taking up space explains how those snapshots behave.
How long does it stay?
Apple doesn't say. It says Time Machine removes its snapshots as they age or as space is needed, and that your Mac counts snapshot space as available. In practice, a day or two after an update, System Data usually comes back down by itself.
How do you remove it sooner?
If you need the space now, use Time Machine's own setting. Choose Apple menu › System Settings, click General, then Time Machine. Click Options, set Backup Frequency to Manually, click Done, wait a few minutes, then set it back.
Time Machine deletes its local snapshots while automatic backups are off. You lose the ability to restore files from them; backups on your Time Machine disk aren't affected. To remove one snapshot, select it in Disk Utility's snapshot list and click Delete Snapshot.
What if Time Machine can't back up any more?
macOS 27 dropped support for the Apple Filing Protocol, AFP. Apple says Time Machine backups to an AirPort Time Capsule use it, so they stop working after the upgrade.
When backups fail, Time Machine keeps the snapshot of your last successful backup until space is needed. A Mac that backed up to a Time Capsule can find that snapshot growing week by week after the upgrade. Set up a new backup disk, then remove the old one in Time Machine settings with Forget Destination.
Apple Intelligence downloads
On Macs that support it, Apple Intelligence is often the largest permanent change after an upgrade to macOS 27. Its models are counted under macOS, not System Data.
How much space does Apple Intelligence take?
Apple says it needs up to 14 GB on Macs with M3 or later and at least 12 GB of unified memory, and up to 8 GB on other Macs that support it. Intel-based Macs don't support Apple Intelligence, so they download nothing.
On macOS 27, MacRumors and Ars Technica reported Storage settings lines from about 14 GB on an M1 MacBook Air to 22.42 GB on an M3 MacBook Air. Owners posted figures up to about 30 GB, some from release candidate builds. Apple hasn't said whether its own figures are measured the same way.
Does it download by itself?
On macOS 27, yes. Apple says the next generation of Apple Intelligence is automatically available on eligible devices when you update to the 27.0 releases, in supported languages and regions. MacRumors reports there's no longer a switch to stop the download.
That's why the macOS figure can keep rising for a day or so after the upgrade. The download happens in the background, so the space appears after the update itself has finished.
What about macOS 26 Tahoe?
On macOS 26, Apple Intelligence has an on and off switch in System Settings › Apple Intelligence & Siri. The catalog's entry for the models says macOS manages them after you turn it off, and the space may not come back right away.
Can you remove the models?
There's no supported way. The models live in protected system folders that only macOS can change, and Apple offers no button to delete them. This site doesn't recommend third-party scripts that try.
The post on how much space Apple Intelligence uses goes through the figures, the macOS 27 settings and what you can and can't change.
Spotlight reindexing after an update
Spotlight keeps an index of what's on your Mac so you can search it. Apple says indexing happens when you first set up a device, after you install a software update or upgrade, and as data changes.
How long does reindexing take?
Apple says that depending on how much data you have, it can take hours or even days, and that later updates to the index are much faster. It finishes sooner when the Mac isn't in use, is connected to power, and is online over Wi-Fi or Ethernet.
The last condition matters for space. Apple says the connection is needed in case email or other data has to be downloaded for indexing. So a Mac can take on some data during this time, on top of the index itself.
How do you know it's still indexing?
Press Command–Space bar. Apple says that while indexing is in progress, a progress indicator appears at the top of the Spotlight window. Mail may also tell you that its indexing is incomplete.
Does the index take much space?
Normally not. The index is a small part of the disk, but the catalog's entry notes that some people have seen it grow to well over 100 GB when indexing goes wrong. A rebuild after an update is normal; an index that keeps growing for weeks isn't.
What if indexing never seems to finish?
Give it a few days on power first. If searches still miss things, or Spotlight keeps indexing, rebuild the index once: in System Settings › Spotlight, click Search Privacy, add your startup disk, wait a few seconds, remove it again, and click Done.
The post on the Spotlight index covers how to tell a runaway index from a busy one, and how to keep it small.
The Relocated Items folder
You may find a Relocated Items folder after an upgrade and wonder whether it's the reason your disk is full. It almost never is, but it's worth knowing what it is before you remove it.
What is the Relocated Items folder?
Apple's article on the read-only system volume explains it. Since macOS Catalina, macOS runs from its own read-only volume, separate from your files. When the upgrade created that arrangement, files that couldn't be moved to their new location were placed in /.
Apple says the folder comes with a shortcut on the desktop and a PDF with more details about the files. It suggests checking the folder for any files you can't find after the upgrade.
What's inside it?
Usually settings files from macOS's own configuration folders. If one of those files had been changed, by you or by an app, an upgrade can keep your version and put macOS's copy aside. One developer, Ruben Schade, found exactly that with a shell settings file he'd edited.
On one Mac running macOS 27, checked for this post, the newest folder held no PDF. It held a Configuration folder with copies of macOS's default settings for remote login and the time zone, with names ending in .system_default, and came to about 60 KB.
What if you changed a settings file on purpose?
Then your version is usually still in place, and the copy in Relocated Items is macOS's own. That's what Schade found: his edited file was kept, and the new default went into the folder.
Compare the two if you know what you changed. Keep your version if it still works, and copy any new lines from macOS's version only if you understand them. Then the folder has done its job.
Why are there several Previously Relocated Items folders?
Later updates can add more. The Mac checked for this post had seven, made over about 18 months: Relocated Items for the newest, and Previously Relocated Items, then Previously Relocated Items 1 to 5, for the older ones, in date order. Each was between 56 and 60 KB.
Can you delete Relocated Items?
Yes, once you've looked. Open the PDF if there is one, and check that nothing inside is a file you changed and want back. If you never edited macOS's settings files, there's nothing in it you need.
The folders belong to the system, so Finder asks for an administrator's name and password to move them to the Trash. The desktop shortcut is only a shortcut: removing it removes nothing else.
Does it explain a full disk?
No. Relocated Items holds a handful of small text files. If space went missing after an update, the snapshot, Apple Intelligence or an installer are far more likely. Because it's in the Shared folder, Storage settings counts it with Other Users & Shared.
Installer leftovers
An update can leave installer files in three or four places. Only one of them is large and yours to remove, and the rest belong to macOS.
| Leftover | Where it is | Size | What to do |
|---|---|---|---|
| Full installer app | /Applications | About 13 to 20 GB | Move it to the Trash if you don't need it |
| Installer packages and disk images | ~/Downloads | Varies | Move them to the Trash once installed |
| A waiting or staged update | Protected system folders | Several GB | Leave it to Software Update |
| Software Update's folder | /Library/Updates | Usually small | Leave it; install pending updates |
| macOS Install Data folder | The top level of the startup disk | Varies | Finish the update; don't delete it by hand |
The full installer app
If you upgraded with a full installer, or downloaded one from the App Store, an app named Install macOS and the version name may still be in your Applications folder. The catalog's research puts these at about 13 to 20 GB.
You don't need it to keep using your Mac or to reinstall macOS, which macOS Recovery downloads for you. Keep it only if you want to make a bootable installer or install the same version on another Mac. Otherwise, move it to the Trash and empty the Trash.
The post on deleting old macOS installers covers every kind, including iPhone software files and installer packages.
The downloaded update itself
Software Update keeps an update's files in protected system folders while it waits to install, and removes them once the update is done. Apple says that when space is needed, macOS also clears staged macOS and app updates by itself. Leave these to Software Update.
If an update didn't finish installing, it can leave files in /. The catalog's advice is to install pending updates in System Settings › General › Software Update, and let macOS remove what it no longer needs.
A macOS Install Data folder
A folder named macOS Install Data at the top level of your startup disk means an installation started and may not have finished. Apple doesn't document it, and there are reports of Macs that couldn't start up after it was deleted by hand.
Finish or restart the update in Software Update instead, and leave the folder to the installer.
Installer packages and disk images in Downloads
Disk images and packages you downloaded to install apps, or a macOS installer you downloaded from Apple's site, stay in Downloads until you remove them. Once you've installed what they contain, they're usually safe to move to the Trash.
Should you turn off automatic downloads?
Only if downloads arriving unannounced are the problem. In System Settings › General › Software Update, click the information button next to Automatic Updates and turn off Download new updates when available. Your Mac then asks before downloading.
That changes when an update arrives, not how much room it needs. Apple's guide notes that laptops must be plugged in to download updates automatically.
What's different after upgrading to macOS 27
Most of this post applies to any macOS update. A few things are new in macOS 27 Golden Gate, and they explain why an upgrade from macOS 26 Tahoe can leave less free space than earlier upgrades did.
| What | macOS 26 Tahoe | macOS 27 Golden Gate |
|---|---|---|
| Apple Intelligence | A switch in Apple Intelligence & Siri settings | Automatically available on eligible Macs; no single switch |
| Where Siri's settings are | System Settings › Apple Intelligence & Siri | System Settings › Siri |
| Time Machine to an AirPort Time Capsule | Works, over AFP | Not supported |
| Time Machine settings | System Settings › General › Time Machine | The same |
| Storage settings | System Settings › General › Storage, with All Volumes | The same |
Why can macOS 27 leave less free space than macOS 26?
Mostly because of Apple Intelligence. Apple says its next generation is automatically available once eligible devices update to the 27.0 releases, and the figures people report in Storage settings are larger than Apple's own maximums. The snapshot and the reindexing happen with every update, so they aren't new.
Does every Mac get the larger download?
No. Intel-based Macs don't support Apple Intelligence and download nothing for it. Apple's figures depend on the chip and memory: up to 14 GB on Macs with M3 or later and at least 12 GB of unified memory, up to 8 GB on the rest.
Apple also says the features arrive in supported languages and regions, and need the Mac's language and Siri's language set to the same supported language. It doesn't say what a Mac outside those downloads.
What about a Mac that backed up to a Time Capsule?
Its backups stop after the upgrade, because AFP isn't supported in macOS 27 or later. That's easy to miss, since nothing else changes. Check the date of the latest backup in the Time Machine menu, and set up a new backup disk if it has stopped moving.
Apple lists what still works on macOS 27: an external disk connected to the Mac, a Mac shared as a network backup destination, and a NAS that supports Time Machine over SMB. Once the new disk is set up, use Forget Destination on the old one.
Should you make room before upgrading?
Yes, if your disk is nearly full. The update needs working room to install, and on an eligible Mac, Apple Intelligence's download arrives afterwards. Freeing space before you start gives macOS room for both, instead of leaving you short the next morning.
A worked example after upgrading to macOS 27
Say a MacBook Air with M1 and a 512 GB disk had 60 GB free the evening before it upgraded to macOS 27. The next morning, free space looks much lower, and both macOS and System Data have grown in Storage settings.
What the checks show
The macOS category has grown, and its list includes an Apple Intelligence line of about 14 GB, the figure Ars Technica reported for an M1 MacBook Air. That part is permanent.
System Data is also larger. Disk Utility lists a snapshot from just before the update and a row of Time Machine's hourly snapshots. Spotlight's window shows indexing in progress.
What the leftovers add
Applications has no installer, because the upgrade came through Software Update. The Shared folder has a new Relocated Items folder of about 60 KB. Downloads holds an old app installer of 1 GB, which can go.
Two days later
Spotlight has finished. The hourly snapshots have aged out, and in this example the pre-update snapshot has gone too. System Data is back near where it was, and the remaining difference is mostly Apple Intelligence and the newer system.
If that difference matters on this Mac, the answer is elsewhere: iPhone backups, Downloads, caches of apps no longer used, and large files. The post on making room for a macOS update goes through those in order.
What wasn't done
Nothing in a system folder was touched. Time Machine stayed on. No Terminal commands were run, and nothing was deleted that macOS would have removed by itself a day later.
Mistakes to avoid after an update
The days after an update are when the most aggressive advice appears, and when it does the most harm. These are the ones to skip.
Don't reinstall macOS to get the space back
Reinstalling macOS doesn't remove your apps or files, so the space they use stays used, and the newer system and its downloads come back with it. You'd lose a day and gain nothing a little patience wouldn't give you.
Don't delete system folders or protected downloads
The folders that hold update files, Apple Intelligence's models and other downloaded parts of macOS are protected, and only macOS should change them. Leave /, / and anything inside them alone.
Don't turn off Time Machine for good
Removing Time Machine's local snapshots once, to make room, is fine. Leaving automatic backups off afterwards isn't: the snapshot from before the update would have come and gone by itself, and you'd be without backups from then on.
Don't paste Terminal commands from a web page
Guides that promise to "clear System Data" or remove Apple Intelligence with a command are best closed. Commands that delete things can't be undone, and fake cleanup guides are a known way to spread malware.
Don't remove snapshots before you've checked your files
The snapshot from before the update is a way back to your files as they were. If anything looks wrong after the update, such as a document an app converted or settings that changed, restore what you need with Time Machine first, while the local snapshots are still there. Remove snapshots only once you're happy.
Don't judge the numbers on the first day
Storage settings, Spotlight and the snapshot all need time. Measure again after a day on power and a restart, and compare like with like: Storage settings with Storage settings, Disk Utility with Disk Utility.
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. File names and paths never leave your Mac.
System Data, explained splits that one number into named buckets, including local snapshots and macOS's caches and installers, and shows how much it couldn't explain. Its space meter shows how much of the available space is purgeable and how many local snapshots there are.
The menu bar item shows how much space is available and keeps a daily history. Click it to see what changed since yesterday, and, while an update is waiting, whether it fits. It estimates the room needed at twice the download and says it's an estimate.
These are the catalog's entries for what an update changes:
Hourly snapshots of your startup disk that Time Machine keeps on the disk itself, so you can restore files even without your backup disk.
Managed by macOS · Runs tmutil for Time Machine's own snapshots, through the helper
/
System/ Library/ AssetsV2/ com_apple_MobileAsset_UAF_FM_* The on-device language and image models that Apple Intelligence features use.
Managed by macOS · Explained only: never removed
/
System/ Volumes/ Data/ .Spotlight-V100 The index Spotlight keeps for each disk so it can find files, and what's inside them, quickly.
Managed by macOS · Explained only: the app shows you how
/
Applications/ Install {macOS,OS X} *.app Full macOS installer apps, such as Install macOS Tahoe, left in your Applications folder after a download.
Usually safe · Moves it to the Trash
/
Library/ Updates Files Software Update downloads and keeps until an update is installed.
Managed by macOS · Explained only: never removed
Snapshots, Apple Intelligence's models, the Spotlight index and update files are Managed by macOS: explained and handled through macOS's own mechanism, never moved. A full installer app is Usually safe: it comes back only if you download it again, so it waits for your choice.
The menu bar item and its meter are free, it keeps history from the first day, and the alert that there isn't room for a macOS update always comes.
What Changed, which shows the last 7 or 30 days and which places grew or shrank, is PRO. So are Cleanup, the Apple Data actions for installers and removing Time Machine snapshots: 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
Why did my storage go down after a macOS update?
Usually because of a snapshot saved before the update, new downloads such as Apple Intelligence's models, and Spotlight building its index again. Storage settings also needs time to work out its figures. Wait a day on power, restart, and look again before removing anything.
Will the space come back after an update?
Part of it. The snapshot from before the update and the busy indexing are temporary, and macOS clears update files it no longer needs. A newer system and, on macOS 27, Apple Intelligence's models stay.
Is it safe to delete the Relocated Items folder?
Yes, once you've checked that nothing inside is a file you changed and want back. It usually holds copies of a few small settings files, so removing it frees almost nothing. Finder asks for an administrator's password because the folder belongs to the system.
Why is System Data bigger after updating macOS?
The snapshot macOS saves before an update, and Time Machine's hourly snapshots, hold on to everything the update changed, and Storage settings counts that space in System Data. It usually comes back down within a day or two as they're removed.
Can I delete the macOS installer after updating?
Yes, if an Install macOS app is still in your Applications folder and you don't need it to make a bootable installer. You don't need it to reinstall macOS, which macOS Recovery downloads for you. Move it to the Trash and empty the Trash.
Why is my Mac slow and its disk busy after an update?
Spotlight indexes your Mac again after an update or upgrade, and Apple says that can take hours or even days. It finishes sooner when the Mac isn't in use and is connected to power and the internet. Apple Intelligence may also be downloading in the background.
Can I stop macOS 27 from downloading Apple Intelligence?
Apple says the next generation of Apple Intelligence is automatically available on eligible Macs after updating to macOS 27, and MacRumors reports there's no switch to stop the download. On macOS 26 Tahoe, Apple Intelligence still has an on and off switch.
Sources
- About the read-only system volume in macOS Catalina or later · Apple
- About Time Machine local snapshots · Apple
- About Spotlight indexing and search results on Apple devices · Apple
- How to get the next generation of Apple Intelligence · Apple
- Backup disks you can use with Time Machine · Apple
- Apple Intelligence Taking Up 30GB+ on Some Macs Running macOS 27 · MacRumors