Time Machine Local Snapshots Taking Up Space? What to Do

Written for macOS 27 Golden Gate and macOS 26 Tahoe.

You delete a big folder, empty the Trash, and the free space hardly changes. Or a disk tool tells you something is holding tens of gigabytes that Finder can't see. Often the answer is local Time Machine snapshots. They're designed to clean up after themselves, and usually they do. This guide explains what they are, how to see them, and how to clear them safely when you need the space now.

#Key takeaways

• Time Machine takes a local snapshot about every hour and keeps it for 24 hours, plus one of your last successful backup.
• Apple counts snapshot space as available and deletes snapshots when space is needed. You rarely have to do anything.
• Snapshots keep deleted files on disk until they expire, which is why deleting files can free less space than you expect.
• Apple's way to clear them is to switch Backup Frequency to Manually for a few minutes, then switch it back.
• Not every snapshot belongs to Time Machine. Leave the com.apple.os.update snapshot alone.

#What are Time Machine local snapshots?

They are point-in-time copies of your startup disk, stored on that same disk. Apple's support article spells out the rules:

• Time Machine saves a snapshot of your startup disk approximately every hour and keeps it for 24 hours.
• It keeps an extra snapshot of your last successful backup until space is needed.
• On macOS High Sierra and later, another snapshot is saved before any macOS update is installed.
• Snapshots are stored only on APFS disks, and only while Back Up Automatically is on.

Apple's Mac User Guide frames them as a way to recover earlier versions of files when your backup disk isn't available, such as a laptop away from its desk. It also says they're not a substitute for real backups. If your Mac's disk fails, the snapshots go with it.

#Why do snapshots seem to take up space?

A snapshot records the state of the disk at one moment. Anything that existed then has to stay on the disk while the snapshot exists, even if you delete it afterwards. The Eclectic Light Company puts it simply: the file system has to keep all the storage blocks that were in use when the snapshot was made.

You'll usually notice it in one of these ways:

1. Deleting files frees less than expected. The deleted files still belong to a snapshot until it expires.
2. Big changing files cause big snapshots. Virtual machine images and large media projects change a lot, and the old versions get held. Eclectic Light notes that snapshots always cover whole volumes, so you can't exclude one big file from them.
3. "Available" and "free" disagree. Apple says your Mac counts the space used by snapshots as available storage. Different tools may report it differently.

The good news is in the same Apple article: Time Machine automatically deletes snapshots as they age or as space is needed for other things.

#How do I see my local snapshots?

You can check from Terminal or from Disk Utility. Both ways only look.

In Terminal, list the Time Machine snapshots on the startup disk:

# Lists local Time Machine snapshots on the startup disk (read-only)
tmutil listlocalsnapshots /

# Shows just their dates, formatted YYYY-MM-DD-HHMMSS (read-only)
tmutil listlocalsnapshotdates /

Time Machine snapshots have names that start with com.apple.TimeMachine. followed by a date. On our test Mac running macOS 26 Tahoe, both commands came back empty, which is what you'd expect when Time Machine has nothing held locally.

In Disk Utility, you can see sizes:

1. Open Disk Utility (Applications › Utilities).
2. Choose View › Show APFS Snapshots.
3. Select your data volume in the sidebar (usually Macintosh HD - Data). Its snapshots appear in a table at the bottom of the window.

Eclectic Light explains the two size columns. Private Size is roughly what you'd get back by deleting that one snapshot. Size is cumulative and includes older snapshots it depends on.

If you prefer Terminal, this read-only command lists every APFS snapshot on the data volume, Time Machine or not:

# Lists all APFS snapshots on the data volume (read-only)
diskutil apfs listSnapshots /System/Volumes/Data

#The snapshot you must leave alone

If you run diskutil apfs listSnapshots / (the system volume rather than the data volume), you'll likely see a snapshot named com.apple.os.update- followed by a long string. That isn't a Time Machine snapshot. Apple's Platform Security guide explains that since macOS 11, the system runs from a cryptographically sealed system volume, and APFS snapshots are part of how that works. On our test Mac, diskutil marked it Purgeable: No. Don't try to delete it.

#Which snapshots are safe to remove?

#How do I free the space safely?

Go in this order. Stop as soon as you have the space you need.

1. Wait. If you aren't short on space right now, do nothing. Snapshots older than 24 hours go away on their own, and Time Machine removes them sooner when space runs low.
2. Use Apple's method. Apple says to turn off automatic backups temporarily. On macOS 27 and 26, open System Settings › General › Time Machine, click Options, set Backup Frequency to Manually, and click Done. Wait a few minutes, then set it back to your usual frequency. Don't forget the second half. Leaving it on Manually means no automatic backups.
3. Delete specific snapshots in Disk Utility. With View › Show APFS Snapshots turned on, select the data volume, select one or more snapshots in the table, then click the Delete Snapshot button. There's no undo. Eclectic Light suggests you can remove all Time Machine snapshots except the most recent one, which the next backup needs. Without it, the next backup could be a full one.
4. Thin from Terminal, if you're comfortable. tmutil thinlocalsnapshots asks Time Machine to remove snapshots until a set amount of space (in bytes) is free, with an urgency from 1 to 4:

# WARNING: removes local Time Machine snapshots until about 20 GB is reclaimed.
# Snapshots can't be recovered afterwards. Your backups on the backup disk are not affected.
sudo tmutil thinlocalsnapshots / 20000000000 4

We took this syntax from the tmutil manual page on macOS 26 Tahoe and didn't run it on our test Mac, because it removes data. Apple's Manually method above does the same job without Terminal.

After any of these, check System Settings › General › Storage again. It can take a few minutes for the numbers to catch up.

#What not to do

• Don't delete the com.apple.os.update snapshot, or any snapshot on the system volume.
• Don't delete snapshot folders with rm, even if a guide suggests it. Use Time Machine, Disk Utility or tmutil.
• Don't leave Time Machine on Manually after clearing snapshots. You'd be trading a little disk space for no backups.
• Don't treat local snapshots as your backup. They live on the same disk they protect.
• Don't clear snapshots right after a macOS update unless you need the space. The pre-update snapshot is a safety net for the first day.
• Don't trust a tool that removes "snapshots" without showing their names. You want to know exactly which ones go.

#Where the rest of the space went

Once snapshots are ruled out, the space is usually in ordinary folders: caches, old installers, device backups or files from apps you no longer use. A disk map makes that quick to see. Remember the snapshot rule, though. Files you delete while a snapshot still holds them won't free space until that snapshot expires.

Freshist's Analyze view draws your disk as a treemap, hardlink-aware so nothing is counted twice, and its cleaner lists every item before moving it to the Trash. Scanning is free. See the help docs, how it compares or pricing. For individual folders, our cache guides and Library folder guide explain what each location holds.

#Related guides

• What is System Data on Mac?
• Lost storage after the macOS 27 update? Here's why
• Developer caches on Mac: virtual machines and build folders are common snapshot hogs.
• How to completely uninstall apps on Mac
• Mac cleaner without a subscription: what to check

#Sources

• Apple Support: About Time Machine local snapshots
• Apple Mac User Guide: About Time Machine local snapshots on Mac
• Apple Disk Utility User Guide: View APFS snapshots in Disk Utility on Mac
• Apple Platform Security: Signed system volume security
• Apple Mac User Guide: Change Storage settings on Mac
• The Eclectic Light Company: Take control of snapshots
• The Eclectic Light Company: How did Golden Gate affect free disk space?
• macOS manual page: man tmutil (checked on macOS 26 Tahoe)