How to delete old Time Machine backups on a Mac

Backups and snapshots are two different things

• Backups live on your backup disk: the external drive, or a network disk. Deleting them frees space on that disk, not on your Mac.
• Local snapshots live on your Mac's own disk, and only while automatic backups are on. They let you get back an earlier version of a file when the backup disk isn't connected. Deleting them is what frees space on the Mac.

When the backup disk is full

Apple's guide says Time Machine deletes older backups to make room for new ones as the backup disk fills, though that can take a long time. If you'd rather make room now, back up less:

1. Open System Settings, click General, then Time Machine.
2. Click Options.
3. Click the Add button and choose a large folder you don't need backed up, such as a downloads folder or a virtual machine. Then click Save.

That stops it being backed up from now on; the copies already on the disk age out as usual. The other answer Apple gives is a bigger, or a second, backup disk.

Deleting a particular backup, with tmutil

Apple's guide gives no way to delete a backup in Finder. The tool for it is tmutil in Terminal. With the backup disk connected (change Backup Disk to your disk's name), list the backups:

sudo tmutil listbackups -d "/Volumes/Backup Disk"

Each backup is named by its date and time. To delete one, give that timestamp:

sudo tmutil delete -d "/Volumes/Backup Disk" -t 2026-01-15-093012

Both need your administrator password, and Terminal needs Full Disk Access in System Settings → Privacy & Security. Backups share unchanged files with each other, so deleting one may free less than you expect. Never delete the most recent backup: it is the one you would restore from.

Old backups from a Mac you no longer have

tmutil delete can also remove backups another Mac made. If the disk holds nothing but an old Mac's backups and you are sure you don't need them, the simpler route is to erase the disk in Disk Utility and choose it again in Time Machine settings, so it starts afresh. That deletes everything on the disk, so copy off anything you want first.

Local snapshots on your Mac

Time Machine saves a snapshot of your startup disk about every hour and keeps it for 24 hours. It also keeps one of your last successful backup until the space is needed, and saves one before each macOS update. Apple's own note is that your Mac counts the space used by snapshots as available storage, and they are removed as they age or when space is needed. So they rarely stand in the way. To see them:

tmutil listlocalsnapshots /

Is it safe to delete them? Yes, if your backup disk is up to date. You only lose the hourly points to go back to while the disk is away. Apple's way to clear them:

1. Open System Settings → General → Time Machine and click Options.
2. Set Backup Frequency to Manually.
3. Wait a few minutes while the snapshots are deleted, then set it back to automatic. Time Machine remembers your backup disks.

To delete the snapshot for one date in Terminal, use the date from the list above:

sudo tmutil deletelocalsnapshots 2026-11-09-101500

A snapshot macOS saved before an update may not go, whatever you ask: macOS marks it as not purgeable. That is why a Mac can show snapshots that deleting doesn't shift. For where snapshot space appears in Storage, see System Data and purgeable space.

Where the app comes in

In the download edition, RefreshYourMac's maintenance jobs include Thin local snapshots. Before you press Run, it counts how many of your snapshots macOS is willing to drop, and says so plainly when every one was made for an OS update and thinning would free nothing. It never touches the backups on your backup disk. For the rest of a full Mac, see Mac storage full?, and for iPhone and iPad backups, which are a different kind of backup, see old iPhone backups.