Not enough space to install macOS? How to make room for the update

If your Mac says there's not enough space to install macOS, it needs more truly free space on the startup disk than it has right now: room for the download, and working room to install it. The fix is to make that room before you try again, and the order you do it in matters.

Some space comes back in minutes: the Trash, old installers, iPhone software files and Time Machine's local snapshots. Some takes a decision, such as old iPhone backups and large files you could keep on another drive. And some only looks free: Finder counts space macOS can free later as available, while the installer wants it free now.

Apple doesn't publish one figure for most updates, so the target is enough room for Software Update to go ahead, plus a margin for the days after the update. This post goes through where that space usually is, in the order worth trying, and what to do if the installer still says no.

How much space does a macOS update need?

More than the download. The installer has to keep the download, unpack it and stage the new system before it restarts. If you use Time Machine, macOS also saves a local snapshot of your disk before installing. All of that needs free space at the same time.

Why does it need so much more than the download?

The download is compressed, and the installer works with it in stages. In tests of macOS Ventura in 2022, Eclectic Light found that a point update with a download of about 2.5 GB asked for about 13 GB of free space before it would start. Major upgrades download much more, and need more room still.

The space is needed only while the update installs. Most of the working room comes back afterwards, which is why a temporary measure, such as safe mode, can be enough to get an update through.

What does Apple say about it?

Apple's guide to troubleshooting updates says that if the message says your Mac doesn't have enough storage space, you should free up storage space. Its guide to downloading macOS adds a useful detail: Software Update can use less storage space to download and install updates than the other methods.

So use System Settings › General › Software Update rather than downloading a full installer from the App Store, unless you need the installer for something else. A full installer app sits in your Applications folder and takes many gigabytes of its own.

An Apple engineer put the limit plainly on Apple's developer forums: "Disk space is a hard limit." There's no setting that lets an update install without the room it needs.

Do automatic downloads take space too?

Yes, until they're installed. With Download new updates when available turned on in Software Update's automatic update settings, your Mac downloads updates in the background and keeps them ready. An update that's downloaded but not installed takes space like any other file.

Apple says that when space is needed, macOS clears staged macOS and app updates, among other things it knows are safe to remove. That keeps a waiting download from filling the disk, but it also means a staged update may have to download again when you finally install it.

Can every Mac install macOS 27?

No. Apple lists macOS 27 Golden Gate as compatible only with Macs with Apple silicon: MacBook Neo, MacBook Air, MacBook Pro and Mac mini from 2020 and later, iMac from 2021 and later, Mac Studio from 2022 and later, and Mac Pro from 2023.

On an Intel-based Mac, Software Update offers macOS 26 Tahoe and its updates instead, if the Mac supports it. Everything in this post applies to those updates just the same.

Kind of update	Example	How it arrives	What to know about space
Update within your version	27.0 to 27.1	Software Update	Can need several times its download size free while installing
Upgrade to a new version	Tahoe 26 to Golden Gate 27	Software Update	The largest download, and the most working room
Full installer app	Install macOS Golden Gate	App Store or Software Update	Stays in Applications until you remove it

Check how much space is really free

Before you remove anything, find out how much you actually have. Three places on your Mac answer the question, and they don't agree, because they count different things.

Which number should you trust?

Open Disk Utility, in the Utilities folder inside Applications, select your startup disk's volume, and click the Info button in the toolbar. Disk Utility lists used, purgeable and free space separately, and the free figure is what's there right now.

Finder's available figure, in a window's status bar or in File › Get Info on the disk, includes purgeable space: space macOS says it can free when something needs it. Storage settings, in System Settings › General › Storage, shows used and available space by category and works its figures out in the background.

Where	What it shows	Use it for
Disk Utility	Used, purgeable and free, separately	The free space an installer can use now
Finder	Free plus purgeable space, as available	A rough idea, not the installer's view
Storage settings	Used and available, by category	Finding what to remove
Software Update	Whether there's room to go ahead	The final word

Why does Finder say there's room when the installer says there isn't?

Usually because of purgeable space. Time Machine's local snapshots and iCloud Drive files macOS could remove from this Mac count as available, but they're still on the disk until macOS removes them. An installer that checks for room can find too little before that happens.

Apple says your Mac counts the space snapshots use as available, and that Time Machine removes them as they age or when space is needed. The guide to purgeable space explains the rest. The section below shows how to free that space yourself.

Not enough space to install macOS: the quick wins

Start here. Each of these takes a few minutes, needs no new drive, and removes only things you can get back or no longer need.

Empty the Trash

Items in the Trash still take space. Click the Trash in the Dock, look through it, then click Empty, or choose Finder › Empty Trash. Each external drive has its own Trash, emptied only while it's connected; it doesn't help your startup disk.

Apps keep bins of their own: Photos and Messages keep deleted items in Recently Deleted for up to 30 days, and Mail keeps deleted messages until you erase them with Mailbox › Erase Deleted Items.

Remove old macOS installers

If you once downloaded a full installer and didn't run it, an app named Install macOS and a version name, such as Install macOS Tahoe, may still be in your Applications folder. It takes many gigabytes.

You only need it to install that version again or to make a bootable installer, and Apple lets you download installers again for the versions your Mac supports. Move it to the Trash, then empty the Trash. If Software Update offers the version you want, you don't need the installer app at all.

Remove iPhone and iPad software files

When you update or restore an iPhone or iPad from Finder, macOS keeps the software file, several gigabytes each, and leaves it behind. Finder downloads the current version again when it needs one, so these are safe to remove.

Open System Settings › General › Storage, click the information button next to iOS Files, and look for software updates in the list. Select the ones you don't need and click Delete. The same list shows backups, which need more thought; see the next section.

Remove downloads of iCloud Drive files

If you use iCloud Drive, your Mac keeps a copy of the files you've opened. In Finder, open iCloud Drive, Control-click large files or folders you don't need on this Mac, and choose Remove Download. They stay in iCloud and on your other devices.

Don't delete them instead. Deleting a file in iCloud Drive deletes it from iCloud and from every device that uses it.

Remove Time Machine's local snapshots

If you back up with Time Machine, local snapshots can hold tens of gigabytes that Finder already counts as available. Time Machine removes them by itself as they age or when space is needed, but an installer can ask first.

To remove them now, open System Settings › General › Time Machine, click Options, set Backup Frequency to Manually and click Done. Wait a few minutes, then set it back after the update. You can no longer restore files from the removed snapshots; backups on your Time Machine disk aren't affected.

The guide to Time Machine local snapshots shows how to see them in Disk Utility, and how to remove one at a time.

Bigger moves when the quick wins aren't enough

If the quick wins don't free enough, the next places take a decision, because some of what's there may be the only copy of something. Take them one at a time, and check before you remove.

• Old macOS installers13–20 GB · Usually safe
• iPhone software files5–15 GB · Safe
• App caches2–30 GB · Safe
• Xcode DerivedData5–100 GB · Safe
• iPhone and iPad backups10–200 GB · Review first
• Messages attachments5–100 GB · Review first
• Downloads and large old files5–100 GB · Review first

Typical ranges on Macs that have these items at all, from the research behind the app's catalog. iPhone software files are per file. Many Macs have far less.

Old iPhone and iPad backups

Every device you back up to this Mac keeps a backup that can take tens of gigabytes. Backups of devices you no longer have stay until you delete them. In Storage settings, click the information button next to iOS Files, select a backup and click Delete.

A backup may be the only copy of what's in it. Before deleting a current device's backup, check on the device that it backs up to iCloud. An encrypted backup also holds saved passwords, Wi-Fi settings and Health data. The iPhone backups guide covers moving them instead.

Downloads and large files

Open Storage settings, click the information button next to Documents, and switch to the view of large files. Sort by Last Accessed: a video or disk image you haven't opened in a year is a good candidate. In Downloads, disk images and installer packages of apps you've already installed can usually go.

For anything you want to keep, copy it to an external drive, open the copy to check it works, then remove the original. That frees the space without losing anything.

Messages attachments and the Photos library

Messages keeps every photo and video in your conversations. Click the information button next to Messages in Storage settings to see the largest attachments and delete the ones you don't need. With Messages in iCloud, deleting on your Mac deletes on your other devices too.

The Photos library can be made smaller only in Photos: turn on Optimize Mac Storage in Photos' iCloud settings if you use iCloud Photos, or move the library to an external drive. Never delete files inside the library in Finder.

Caches and developer files

Caches are safe to clear and come back as you use your apps, which is fine here: you need the room for an hour, not forever. Quit an app, then move its folder in ~/Library/Caches to the Trash. The post on how to clear cache on a Mac goes through every kind.

On a developer's Mac, Xcode's DerivedData, unused simulator runtimes, Docker images and local AI models often hold the most. Remove them with each tool's own controls, such as Xcode's Components settings for runtimes.

Accounts nobody uses any more

Storage settings counts other accounts' files under Other Users & Shared, and you can't see or remove them from your own account. If someone no longer uses this Mac, an administrator can delete their account in System Settings › Users & Groups: click the information button next to the user, then Delete User.

Choose Delete the home folder to free the space. Save the home folder in a disk image keeps everything in /Users/Deleted Users, where it still takes space until someone checks it and removes it.

Store in iCloud and Optimize Storage

Storage settings' recommendations hand space to iCloud over time: Store in iCloud keeps Desktop and Documents files, photos and messages in iCloud, with only recent items on the Mac when space is needed. They need room in your iCloud plan, and they work as files upload, not in the next five minutes.

They're the right long-term answer for a small disk, but not a quick fix in the hour before an update. Turn them on early, and use the steps above for the update itself.

Apps you no longer use

In Storage settings, click the information button next to Applications to see your apps by size. Large apps you've stopped using, such as games and video editors, can go to the Trash; use an app's own uninstaller if it came with one.

Where to look	Typical find	Level	Where to remove it
Trash	Everything you deleted	Review first	The Trash, then Empty
Applications	An Install macOS app	Usually safe	Finder
iOS Files	iPhone software files	Safe	Storage settings
iOS Files	Old device backups	Review first	Storage settings, or Finder
iCloud Drive	Downloaded copies of files	Usually safe	Finder, Remove Download
Time Machine	Local snapshots	Managed by macOS	Time Machine settings
~/Library/Caches	App caches	Safe	Finder, with the app quit
Documents and Downloads	Large old files	Review first	Finder, after a copy

Try the update again, the right way

Once Disk Utility shows enough free space, go back to Software Update. A few habits make the second attempt more likely to finish.

Back up first

Apple recommends backing up before you install an update. With Time Machine, connect your backup disk and choose Back Up Now from the Time Machine menu in the menu bar, or wait for the next automatic backup. A backup on another disk takes no room on your Mac.

If you turned off automatic backups to remove local snapshots, a manual backup still works. It also means you have a recent copy of everything before you start removing the larger items above.

Restart before you try

A restart clears the swap files macOS uses as extra memory, which can be several gigabytes, and lets apps let go of temporary files. Restart, then open Software Update before opening anything else.

Use safe mode if you're only a little short

Apple says starting up in safe mode clears some system caches, which may give you enough space for a task that needs it only while it runs, such as installing a macOS update. Apple's troubleshooting guide also suggests safe mode when you install from Software Update.

On a Mac with Apple silicon, shut down, press and hold the power button until you see Loading startup options, select your startup disk, hold Shift and click Continue in Safe Mode. On an Intel-based Mac, hold Shift as it starts up, until the login window appears. Then open Software Update.

Let Software Update download it again if it's stuck

If an installer you downloaded earlier is reported as damaged or can't be verified, Apple says to repair the disk, then delete the installer and download a new copy from Apple. Move an old Install macOS app to the Trash before you try again, so you aren't keeping two copies.

In Software Update, click the information button next to Automatic Updates to see whether Download new updates when available is on. If it is, your Mac may already hold a downloaded update, and installing it lets macOS remove the files it no longer needs.

Plug in, and leave it alone

Keep a laptop on its power adapter, and don't close the lid or put the Mac to sleep. Apple says your Mac may restart several times while it installs. Opening apps during the update uses space and memory it may need.

A worked example

Say Software Update says there isn't enough space for an upgrade. Finder shows 45 GB available, but Disk Utility shows 18 GB free and 27 GB purgeable. The gap is the clue: most of the "available" space is held by local snapshots and iCloud downloads macOS hasn't removed yet.

Start with what's quick. The Trash holds 4 GB, and an old Install macOS app in Applications holds 15 GB more. Emptying both brings the free figure to 37 GB without touching anything you use.

Next, set Time Machine's backup frequency to Manually for a few minutes, so its local snapshots go. Disk Utility now shows most of the purgeable space as free. Restart, open Software Update first, and install.

If it had still been short, the next stops would have been iPhone software files in iOS Files, then old device backups, then large files you could copy to an external drive. Afterwards, turn automatic backups back on, and let the Mac settle for a day before judging how much space you have.

When the installer still says no

If you've freed what you can and the installer still reports an error, Apple's troubleshooting guide goes through the next steps in order. Its messages include that an error occurred while downloading, preparing or installing, that the installer is damaged or couldn't be verified, and that your Mac doesn't have enough storage space.

Apple's step	What it does	When it helps
Free up storage space	Gives the installer room	The message mentions storage
Check your internet connection	Lets the installer download macOS and data for your Mac	The download fails or stalls
Install from macOS Recovery	Keeps other software from interfering	Installing in macOS keeps failing
Repair the startup disk	Runs Disk Utility's First Aid in Recovery	Before downloading a damaged installer again
Revive or restore the firmware	Rare; Macs with Apple silicon or the T2 chip	Problems that persist after everything else
Erase your Mac	Starts again from an empty disk	Nothing else has worked

Repair the disk in macOS Recovery

Apple suggests repairing the startup disk with Disk Utility from macOS Recovery. On a Mac with Apple silicon, shut down, press and hold the power button until you see Loading startup options, click Options, then Continue.

On an Intel-based Mac, shut down, press and release the power button, then press and hold Command-R until you see an Apple logo or a spinning globe.

In Recovery, open Disk Utility, select your startup volume and click First Aid. Then restart and try the update again.

Install from macOS Recovery

macOS Recovery also has Reinstall macOS, which Apple suggests because it keeps other software from interfering with the install. Apple says reinstalling doesn't remove your apps or personal data, though a backup first is still wise. It needs free space on the disk too, so do the steps above first.

Erase and install, as a last resort

If nothing else works, Apple's last step is to erase your Mac. Back up first, and check the backup opens. On a Mac with Apple silicon or the T2 chip, System Settings › General › Transfer or Reset › Erase All Content and Settings erases your data, settings and apps but keeps the installed version of macOS.

After that, install the update on the empty disk, then restore your files from the backup with Migration Assistant. It's slow, and it brings back everything you restore, so it's worth it only when the other steps have failed.

After the update: keep some room free

An update that only just fits leaves a Mac with almost no space, and that brings its own problems. The days after an update are when you want the most headroom.

Why is free space lower right after the update?

If you use Time Machine, macOS saved a local snapshot before the update, and like any snapshot it holds on to space until it's removed. Storage settings also needs time to work out its figures again. Give it a day, and a restart, before you judge.

If you turned off automatic Time Machine backups to remove snapshots, turn them back on now. Your next backup brings your Time Machine disk up to date.

Will Apple Intelligence need more space?

If you use Apple Intelligence, yes. Apple says it needs up to 8 GB of storage, or up to 14 GB on Macs with M3 or later and at least 12 GB of unified memory. Storage settings counts the models under macOS, not System Data.

If you don't use it, you can turn it off in System Settings › Apple Intelligence & Siri. macOS manages the models after that, and the space may not come back right away.

How much free space should you keep?

Apple doesn't publish a figure. What matters is room for the next large thing your Mac does by itself: the next update, a backup, a download. When a disk fills right up, apps can fail to save their own data; in one report on Apple's developer forums, Mail couldn't save mailbox information.

A good habit is to free the space for the next update in advance, rather than in a hurry when it arrives. If you keep running short after removing what you can, what's left is your own data, and the answer is more room: an external drive for archives and video, or a larger iCloud plan.

Where did System Data go?

After an update, System Data often shrinks again as the snapshot taken before it ages out. If you want to know what's in it on your Mac, see what System Data on a Mac is made of.

Mistakes to avoid when you need space for an update

Running short of space before an update makes it tempting to delete things quickly. These are the moves that cost more than they save.

Don't delete system files or whole Library folders

Leave /System, /private/var and the Library folder itself alone, along with the Caches, Application Support and Containers folders as a whole. macOS protects most of it, and removing the rest can break apps or lose data. Remove single items you've identified instead.

Don't delete iCloud Drive files to free local space

Deleting a file in iCloud Drive removes it from iCloud and from your other devices. Remove Download frees the space on this Mac and keeps the file everywhere else.

Don't paste Terminal commands from a web page

Guides that ask you to paste a command to make room for an update are ones to close. Commands that delete files can't be undone, and fake cleanup guides are a known way to install malware. Everything here works through Finder, System Settings and the apps themselves.

Don't install with a disk that's nearly full afterwards

If the update fits only just, free a little more first. A disk with almost no space after an update leaves no room for the next one, for your next backup, or for apps to save their data.

How the app does it

Wombit is a native Mac app that 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.

Its space meter shows the available space beside a bar that ends in what's truly free, and Why the numbers differ says how much of the difference is purgeable and how many local snapshots there are. The menu bar item keeps the available space in view.

When macOS says an update is waiting, the menu bar item asks Apple's update server how big it is, once per update, the way System Settings does. Because Apple doesn't publish a figure for most updates, it estimates the room needed at twice the download, and says it's an estimate.

It alerts you only when there isn't room, and that alert comes whether or not you have Pro. Treat it as an early warning: Software Update has the final say, and it may ask for more.

The places in this post are entries in the app's catalog, written and checked by hand with sources:

• /Applications/Install {macOS,OS X} *.app

  macOS installers

  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/iTunes/{iPhone,iPad,iPod} Software Updates

  iPhone and iPad software updates

  Software files that were downloaded to update or restore an iPhone, iPad or iPod touch connected to this Mac.

  Safe · Moves it to the Trash

• ~/Library/Application Support/MobileSync/Backup/*

  iPhone and iPad backups

  Backups of an iPhone, iPad or iPod touch that were made on this Mac, one folder for each device.

  Review first · Moves it to the Trash

• Time Machine local snapshots

  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

• ~/Library/Mobile Documents

  iCloud Drive

  The iCloud Drive files that are downloaded to this Mac, including the iCloud folders that apps use.

  Usually safe · Explained only: the app shows you how

• ~/Library/Caches/*

  App caches

  Data that apps and macOS services keep so they can load things faster. Apps create it again when they need it.

  Safe · Moves it to the Trash

• ~/.Trash

  Trash

  Items you've moved to the Trash. They still use space until the Trash is emptied.

  Review first · Explained only: the app shows you how

Safe items, such as iPhone software files and app caches, start checked in Cleanup, and only they count in the headline number. Review first items, such as backups and large old files, wait for your choice. iCloud Drive files are never removed by the app; their entry explains Remove Download instead.

The space meter, the menu bar item and the update check are free. Cleanup, the Apple Data actions for iPhone backups, installers and large old files, and removing Time Machine snapshots are 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.