When Time Machine is taking up space on your Mac, the space is almost always in local snapshots. These are copies of your startup disk that Time Machine keeps on the Mac itself: one about every hour for 24 hours, plus one of your last successful backup.
Your backups themselves live on the backup disk, not on your Mac. The one exception is when your Mac is the backup destination for another Mac on your network.
Local snapshots hold on to every file you delete or change after they're taken. Most days they come and go unnoticed. They grow when large files change, when you delete a lot at once, and above all when backups stop completing, because the snapshot of your last successful backup stays until the space is needed.
The fixes, gentlest first: let a backup finish, wait for old snapshots to age out, or set Time Machine's Backup Frequency to Manually for a few minutes so it removes its local snapshots. This post goes through each cause, how to spot it, and what each fix costs.
Where Time Machine uses space on your Mac
Time Machine touches your Mac's storage in more ways than most people expect. Here's each one, where its space lives, and how it goes away.
| What | Where the space is | How long it stays | How it goes away |
|---|---|---|---|
| Hourly local snapshots | Your startup disk | About 24 hours | Time Machine removes them as they age |
| Snapshot of the last successful backup | Your startup disk | Until the space is needed | Replaced after the next successful backup |
| Snapshot before a macOS update | Your startup disk | Not documented | macOS removes it |
| Another Mac's backups | A folder you shared as a backup destination | Until you remove them | You, on the Mac that shares the folder |
| Your own backups | The backup disk | Hourly, daily and weekly, until the disk fills | Time Machine deletes the oldest |
The first three always use your Mac's own disk, and the fourth does when the shared folder is on it. The rest of this post is mostly about the first two, because they're the ones that grow.
Why doesn't Storage settings show a Time Machine category?
Because snapshots aren't files in any folder. System Settings › General › Storage adds up the categories it can measure and calls the rest System Data, so the space local snapshots hold ends up there.
That's why a Mac that backs up with Time Machine often has a much larger System Data figure than one that doesn't. The post on what System Data is takes that category apart.
Does Time Machine take space if you don't use it?
Very little. Time Machine makes hourly local snapshots only when it's set up to back up automatically. If you never added a backup disk, you won't have them.
Apple also says a snapshot is saved before any macOS update is installed. Its article doesn't say whether that depends on Time Machine being set up.
Why does Finder say the space is available?
Apple says your Mac counts the space used by snapshots as available storage, and that Time Machine deletes them as they age or as space is needed. So Finder shows plenty of room, while Storage settings shows a large System Data. Both describe the same space, from different sides.
Are all the snapshots Time Machine's?
Not always. Snapshots whose names begin with com.apple.os.update belong to macOS's update process, and others can come from backup apps such as Carbon Copy Cloner, which keep snapshots on their own schedule.
Time Machine's settings don't remove those. Manage a backup app's snapshots in that app, and leave macOS's update snapshots to macOS.
How to tell if Time Machine is taking up space on your Mac
Three checks, all read-only, tell you whether Time Machine is the reason your space doesn't add up. None of them changes anything.
Check when your last backup finished
Click the Time Machine menu in the menu bar. Its top line shows how far the current backup has got, or the date and time of the latest backup. If you don't see the menu, Apple says to check Menu Bar settings, or Control Center settings in some versions, so Time Machine shows its status there.
You can also open System Settings › General › Time Machine, which lists each backup disk with its latest backup. A date days or weeks ago is the first clue: the snapshot of that backup is still on your Mac.
Look for Time Machine snapshots in Disk Utility
- Open Disk Utility, in the Utilities folder of your Applications folder.
- Choose View › Show APFS Snapshots.
- Select your startup disk's data volume, usually Macintosh HD – Data.
Time Machine's snapshots have names that begin with com.apple.TimeMachine, followed by the date and time they were taken. A row of them about an hour apart is normal. One much older than a day is often the snapshot of your last successful backup.
To see sizes, click the More pop-up menu, choose Show Columns and turn on Private Size. It's roughly what deleting that one snapshot would free. The post on APFS snapshots explains the columns, and the snapshots other apps make.
Compare Finder with Disk Utility
Select the same volume in Disk Utility and click the Info button in the toolbar. It shows purgeable space separately from free space, while Finder adds the two together.
A large purgeable figure on a Mac with Time Machine snapshots is the space those snapshots hold. If purgeable is small and snapshots are few, Time Machine isn't your problem, and the space is somewhere else.
What if there are no Time Machine snapshots?
Then Time Machine isn't what's using your space, whatever the size of System Data. The usual causes there are app caches, swap files, app data in your Library folder, developer tools and local AI models.
Look at those in Finder, starting with the folders in your Library folder, before you change any Time Machine settings. Turning backups off won't free space that snapshots never held.
Why Time Machine's local snapshots grow
A local snapshot starts out tiny. It costs space only as your disk changes after it's taken, because APFS keeps the old version of everything the snapshot still points to. So the question is always: what changed, and how long has the snapshot been kept?
Your backup disk has been away
This is the most common reason on a laptop. Apple says Time Machine keeps a snapshot of your last successful backup until space is needed. While the backup disk is at home and you're not, that snapshot stays, holding everything you've deleted or changed since.
A week of travel with a busy laptop can add up. Once you're back and a backup succeeds, that snapshot is no longer the last successful backup, and Time Machine can let it go.
Backups have been failing
The same thing happens when Time Machine tries to back up and can't. A disk that's too small for the next backup, damaged or no longer connected, a network share that's moved, or a destination macOS no longer supports all leave the last-backup snapshot growing.
Hourly snapshots keep coming as Time Machine tries again. Each lasts a day, but the old last-backup snapshot under them never moves on.
Large files that change all day
Virtual machine disks, Docker's disk image, databases, video projects and photo libraries rewrite large amounts of data. Every hourly snapshot holds the old blocks for a day, so a few hours of heavy work can tie up a lot of space.
Excluding those files from backups doesn't help here. Howard Oakley of Eclectic Light points out that a snapshot is of a whole volume, so Exclude from Backups keeps items off the backup disk but not out of local snapshots.
A big clear-out
You move 60 GB of old video to an external drive and delete it. Snapshots taken before the deletion still hold it, so for up to a day your free space barely moves, and longer if one of them is the snapshot of your last backup.
The post on why deleting files doesn't free space covers this and the other reasons space stays in use.
A macOS update
macOS saves a snapshot before installing an update, and an update changes a great deal of the disk. Free space can look low for a day or two afterwards, while that snapshot and the hourly ones age out. The post on storage after a macOS update covers what else an update changes.
How long does Time Machine keep each kind of backup?
The difference between what Time Machine keeps on your Mac and on the backup disk explains a lot. Local snapshots are short-lived; the long history is on the backup disk.
- Hourly local snapshots on your Mac1 days
- Hourly backups on the backup disk1 days
- Daily backups on the backup disk30 days
From Apple's articles on Time Machine. Daily backups cover the past month. Weekly backups stay on the backup disk until it fills up, and the snapshot of the last successful backup stays on your Mac until the space is needed.
A worked example: three weeks away from the backup disk
Say you take a MacBook Air with a 512 GB disk on a three-week trip. Its Time Machine disk stays at home. During the trip you edit video, copy 45 GB of raw clips to a portable SSD, and delete them from the Mac.
What you see
Free space barely moves after the deletion. Storage settings shows System Data much larger than before the trip. Finder still reports plenty of space available, and Disk Utility's Info window shows a large purgeable figure.
In Disk Utility's snapshot list, there's a row of hourly com.apple.TimeMachine snapshots from today, and one dated the day you left. Its Private Size is a little over the 45 GB you deleted, because it also holds everything else you changed on the trip.
What's holding the space
That old snapshot is the one of your last successful backup. Apple says Time Machine keeps it until space is needed, and it was taken while the clips were still on the Mac. The hourly snapshots from today hold almost nothing extra.
What you do
At home, connect the backup disk and choose Back Up Now. When the backup finishes, the old snapshot is no longer the last successful backup, and Time Machine can remove it. Check Disk Utility later the same day.
If you need the space before you're home, the Backup Frequency method removes the old snapshot within a few minutes. Just remember it held files that were never backed up. Here they're safe on the SSD; if they weren't, you'd copy them somewhere first.
Fixes for Time Machine taking up space
Start with the fix that keeps the most. Each of these removes only local snapshots on your Mac. None of them touches the backups on your backup disk.
Let a backup finish
If your last backup is old, connect the backup disk, or join the network it's on, and choose Back Up Now from the Time Machine menu. Let it finish. The snapshot of the old backup can then go, and you get a current backup out of it.
This is the only fix that also leaves you better protected. Give it a few hours and check Disk Utility's list again.
Wait a day
If your backups are current, hourly snapshots age out by themselves after 24 hours, and Time Machine removes them sooner when space is needed. For a large deletion yesterday, the space is usually back today.
Remove Time Machine's local snapshots now
When an update, a large copy or an export needs the space right away, Apple's method is to pause automatic backups.
- Choose Apple menu › System Settings, click General, then click Time Machine.
- Click Options, choose Manually from the Backup Frequency menu, and click Done.
- Wait a few minutes. Time Machine deletes its local snapshots.
- Choose your usual schedule from Backup Frequency again. Time Machine remembers its backup disks.
The steps are the same in macOS 26 Tahoe and macOS 27 Golden Gate. Don't forget step 4: until you do, Time Machine doesn't back up by itself.
Delete single snapshots in Disk Utility
To remove only the oldest, select it in Disk Utility's snapshot list and click Delete Snapshot. Start with the oldest; Oakley warns that deleting snapshots in the middle frees less than you might expect.
He also suggests keeping the most recent Time Machine snapshot, because without it the next backup could copy the whole data volume again. If you only need room for a moment, the Backup Frequency method is simpler.
Remove a backup disk you no longer use
If you've stopped using a disk but it's still listed, Time Machine keeps trying to back up to it, and can keep making local snapshots. In System Settings › General › Time Machine, select the disk, click the remove button, then click Forget Destination.
Forgetting a destination doesn't erase it. The backups stay on the disk, and you can still restore from them by connecting it later.
Which fix fits your situation?
| Situation | Fix | What it costs |
|---|---|---|
| Last backup is days old | Connect the disk and choose Back Up Now | Time for the backup |
| Large deletion in the last day | Wait for snapshots to age out | Nothing |
| An update or copy needs room now | Set Backup Frequency to Manually, then back | Every restore point kept on your Mac |
| One very old snapshot | Delete it in Disk Utility | Files that only it held |
| A disk you no longer use is still listed | Forget Destination in Time Machine settings | Nothing; its backups stay on it |
| Backups to a Time Capsule stopped | Choose a new backup disk | A new first backup |
Why didn't the space come back?
Give it a few minutes: APFS frees a removed snapshot's blocks in the background, and Storage settings works its figures out slowly. Check Disk Utility's Info window rather than Storage settings.
If free space still hasn't moved, the snapshots weren't holding much. Look for the other usual reasons: items still in the Trash, iCloud Drive files kept on the Mac, or copies that share space with each other.
What do you give up?
Files that exist only in a removed snapshot. If you deleted something by mistake this morning and it isn't on your backup disk yet, the local snapshot may be the only copy. Restore it first, then remove snapshots.
To restore, open the folder where the item was, then open Time Machine with Spotlight. Use the arrows or the timeline to go back, select the item and click Restore. Apple says this works from local snapshots when your backup disk isn't available.
Time Capsule and network backups on macOS 27
macOS 27 Golden Gate changed which network backup destinations work, and that affects local snapshots on Macs that were set up years ago.
Why did backups to a Time Capsule stop?
Apple says backups to an AirPort Time Capsule, or to a disk connected to an AirPort Extreme base station, use the Apple Filing Protocol, AFP. AFP isn't supported in macOS 27 or later, so these destinations no longer work after upgrading.
The same goes for a network drive or another Mac that's only reachable over AFP. Apple says Time Machine to a NAS needs the SMB protocol, and that sharing a Mac as a backup destination is recommended only when both Macs use macOS 11 or later.
What happens to local snapshots when backups stop?
Time Machine keeps trying, and keeps the snapshot of your last successful backup on your Mac. The longer it goes on, the more space that snapshot holds. It's one of the quieter ways an upgrade can leave less free space.
What should you use instead?
Apple lists three destinations that still work on macOS 27: an external storage device connected to your Mac, a Mac shared as a network backup destination, and a NAS that supports Time Machine over SMB.
For an external disk, Apple suggests one with at least twice the storage of your Mac, used only for Time Machine. Once the new disk is set up, remove the old destination with Forget Destination, so Time Machine stops trying to reach it.
What about the old backups on the Time Capsule?
Apple says other data transfer to or from these devices uses AFP too, so a Mac running macOS 27 can't reach them there. A new backup disk starts with a full backup and builds its own history from then on.
If you might need something from the old backups, leave the Time Capsule as it is for a while. A Mac still running an earlier version of macOS can open them.
When your Mac holds another Mac's backups
If you shared a folder on your Mac as a Time Machine backup destination, every Mac that backs up to it uses your disk. That space is real, it isn't purgeable, and it grows until the folder's limit or your disk fills.
How do you check?
Open System Settings › General › Sharing. If File Sharing is on, click the info button next to it and look at the Shared Folders list. Control-click a folder and choose Advanced Options to see whether Share as a Time Machine backup destination is on.
The backups are inside that shared folder. Select it in Finder and choose File › Get Info to see how much space it uses.
Can you limit how much it uses?
Yes. In the same Advanced Options, turn on Limit backups to and enter a size. Apple documents this option for shared folders. Backups to that folder then stop growing at that size, and Time Machine deletes the oldest when it's full, as with any backup disk.
A limit is worth setting when the shared folder is on your startup disk, even if you have room today. Without one, the other Mac's backups grow until your disk is full.
Should you delete another Mac's backups?
Not without asking the person who owns that Mac. Their backups may be the only copy of their files. If they've moved to another backup disk, they can remove this destination in their own Time Machine settings first.
Then turn off Share as a Time Machine backup destination on your Mac. Moving the old backups to the Trash is a decision for whoever they belong to.
Keep Time Machine from filling your Mac again
Most of the space Time Machine holds comes back by itself. A few habits keep it from building up in the first place.
Keep backups completing
Connect a laptop's backup disk regularly, or back up over the network if you have a destination that works on macOS 27. Each successful backup lets the old last-backup snapshot go.
Glance at the date of the latest backup in the Time Machine menu now and then. If it's falling behind, find out why rather than living with it, because a backup that doesn't complete costs you both protection and space.
Put heavy-churn files on their own volume
Oakley suggests keeping virtual machines and other large, busy files on a separate APFS volume that isn't backed up. A new volume shares the disk's free space, so it doesn't take space from anything else until you use it.
In Disk Utility, select your startup volume and click the add volume button in the toolbar. Then add the new volume to Time Machine's Exclude from Backups list, in Options.
Does a less frequent schedule help?
Backup Frequency lets you choose how often Time Machine backs up automatically, not only hourly. Apple doesn't say whether a less frequent schedule changes how often local snapshots are made, so don't count on it to save space.
What it does change is how much you can get back. A daily schedule means up to a day of work isn't on your backup disk yet.
Does Time Machine keep snapshots when space is low?
Fewer. Apple says Time Machine stores local snapshots only on disks that have plenty of free space, and deletes them as space is needed for other things. On a nearly full disk, you get fewer ways back, not a full disk.
That's why a 256 GB or 512 GB Mac can feel tight with Time Machine on: free space is always close, so snapshot space is always visible. Keeping some free space lets Time Machine do its job.
Is Time Machine still worth it on a small Mac?
Yes. The backups go to another disk, and the local snapshots on your Mac give space back when asked. Turning Time Machine off saves little space and leaves you without a backup.
What about before a macOS update?
An update needs a lot of truly free space, and macOS doesn't always free snapshot space as fast as the installer asks. If the installer says there isn't enough room, remove Time Machine's local snapshots first. The post on making room for a macOS update goes through the rest.
Time Machine and local snapshots across macOS versions
Local snapshots have been around longer than APFS, and the way you manage them has moved. When you follow older advice, check which version it was written for.
| macOS version | What changed |
|---|---|
| OS X Lion 10.7 | Local snapshots arrive, on portable Macs |
| High Sierra 10.13 | Local snapshots become APFS snapshots; a snapshot before each macOS update |
| Big Sur 11 | Time Machine can back up to APFS disks |
| Ventura 13 | Time Machine moves to System Settings; Backup Frequency replaces Back Up Automatically |
| Tahoe 26 | Same Time Machine settings as Ventura |
| Golden Gate 27 | AFP is gone, so Time Capsule and other AFP destinations stop working |
What does older advice get wrong?
Guides from before macOS Ventura say to deselect Back Up Automatically in System Preferences. On macOS 26 and 27, the same step is Options › Backup Frequency › Manually in System Settings › General › Time Machine.
Advice from the OS X Lion days often turns local snapshots off with a Terminal command. On today's macOS, the supported way to manage them is Time Machine's own settings, with Disk Utility for single snapshots.
When the backup disk is full, not your Mac
Sometimes "Time Machine is taking up space" means the backup disk is full, not the Mac. That's a different problem, with its own rules.
What happens when the backup disk fills?
Apple says Time Machine keeps hourly backups for the past 24 hours, daily backups for the past month and weekly backups for all previous months, and deletes the oldest backups when the disk is full. If it needs more space than that, your Mac tells you.
Why does deleting files on your Mac not shrink the backups?
Because older backups still include them. A file you delete today stays in every backup that already holds it, until Time Machine deletes those backups as they age or to make room. That's the point of a backup: it keeps what you no longer have.
Can you keep other files on the backup disk?
Apple recommends using a Time Machine disk only for Time Machine. If you want to keep other files on the same drive, Apple's suggestion for advanced users is to add a separate APFS volume for them, and to keep the Time Machine volume at least twice the size of your Mac's storage.
Mistakes to avoid
Time Machine's space is easy to misread, and some common fixes cost more than they save.
Don't turn off Time Machine to save space
Leaving Backup Frequency on Manually for good stops the snapshots, and also stops your backups. Local snapshots are your quickest way back to a file from an hour ago, and macOS removes them by itself.
Don't delete backups on your backup disk to free your Mac's space
Backups on an external disk use that disk's space, not your Mac's. Deleting them frees nothing on your Mac and removes history you might need. Time Machine deletes the oldest by itself when its disk is full. To free the backup disk itself, the post on removing old backups covers the safe ways.
Don't paste Terminal commands to remove snapshots
Commands that delete things can't be undone, and fake cleanup guides are a known way to spread malware. Everything in this post goes through System Settings, Disk Utility and the Time Machine menu.
Don't forget to turn automatic backups back on
The Manually setting is meant for a few minutes. Set a reminder if you need to, because Time Machine won't back up by itself until you change it back.
Don't delete a snapshot you might still need
Before you remove snapshots after deleting something by mistake, restore it. Once its last snapshot is gone and it isn't on the backup disk, there's no way back.
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.
Its space meter shows how much of the available space is purgeable and how many local snapshots there are, so you can see when Time Machine is holding space. System Data, explained gives local snapshots their own bucket instead of hiding them in one number.
The Local Snapshots page lists every snapshot: when it was made, which app made it, and whether macOS removes it by itself. This is the catalog entry behind it:
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
Local snapshots are Managed by macOS: explained and handled through macOS's own mechanism, never moved to the Trash. When you choose, the app deletes Time Machine's own snapshots with Time Machine's own tool, or asks Time Machine to remove as many as it can.
Both need an administrator's name and password, through the helper. Because macOS doesn't say what a snapshot holds, the app measures the available space before and after, and shows the difference. It never touches the backups on your backup disk.
Seeing your snapshots is free. Removing Time Machine snapshots 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
Does Time Machine take up space on my Mac's own disk?
Only through local snapshots, unless your Mac is a backup destination for another Mac. The backups themselves are on the backup disk. Local snapshots last about a day, except the one of your last successful backup, which stays until the space is needed.
Will deleting local snapshots delete my Time Machine backups?
No. Apple says backups on your Time Machine disk aren't affected. You lose only the restore points kept on your Mac, so restore anything you need from them first.
Why is System Data so big when I use Time Machine?
Storage settings has no category for snapshots, so the space they hold is counted in System Data. It shrinks as snapshots age out, or after a successful backup when the old last-backup snapshot can go.
Can I stop Time Machine from keeping snapshots on my Mac?
Only by turning off automatic backups, which also stops your backups. Setting Backup Frequency to Manually for a few minutes removes the current snapshots; then set it back. Keeping backups completing is the better way to keep snapshots small.
Why does Time Machine make snapshots when my backup disk isn't connected?
So you can still restore files from the last day while the disk is elsewhere. Time Machine saves one about every hour and keeps each for 24 hours. When you reconnect the disk, more backups become available.
Can I still use a Time Capsule with macOS 27?
No. Apple says backups to an AirPort Time Capsule use AFP, which isn't supported in macOS 27 or later. Choose an external disk, a Mac shared as a backup destination, or a NAS that supports Time Machine over SMB, and forget the old destination.
How much space do Time Machine local snapshots use?
There's no fixed amount. Each holds what changed or was deleted after it was taken, so they stay small on a quiet Mac and grow with large edits, big deletions and backups that don't complete. Disk Utility's Private Size column gives a rough figure for each.
Sources
- About Time Machine local snapshots · Apple
- Back up your Mac with Time Machine · Apple
- Backup disks you can use with Time Machine · Apple
- Time Machine settings on Mac · Apple
- Back up to a shared folder with Time Machine on Mac · Apple
- Explainer: snapshots · Eclectic Light