Time Machine is Apple’s built-in backup solution. Usually, it backs up your files to an external hard drive. However, if your external drive is unplugged, macOS will quietly create “Local Snapshots”—invisible, massive backup files stored directly on your Mac’s internal SSD. The operating system is supposed to automatically delete these local snapshots when your SSD starts getting full, but the algorithm frequently fails.
When this happens, you might look at your Storage settings and see an enormous grey block labeled “System Data” consuming 50 GB or 100 GB of space. You cannot delete these snapshots via the Finder, because they are deeply embedded in the APFS file system structure. You must use the Terminal to safely list and obliterate these hidden backups.
How to Safely Delete Mac Time Machine Local Snapshots
You must use the tmutil (Time Machine Utility) command in the Terminal to wipe the APFS snapshots.
- Open the Finder, go to Applications, open the Utilities folder, and double-click Terminal (or press Command + Space and search for Terminal).
- First, you should check how many hidden snapshots currently exist on your hard drive. Type the following command and press Enter:
tmutil listlocalsnapshots / - The Terminal will output a list of files that look like this:
com.apple.TimeMachine.2023-10-15-123456.local. (If the command returns nothing, you do not have any local snapshots). - To safely and instantly delete all of these snapshots and reclaim your SSD space, type the following command exactly as written:
sudo tmutil thinlocalsnapshots / 99999999999999 4 - Press Enter. Because this is a core system command, you will be prompted for your administrator password. Type it in (the characters will remain invisible) and press Enter.
The Terminal will output “Thinned local snapshots” and briefly pause as it aggressively purges the APFS volume data. Once the command completes, click the Apple Logo, go to System Settings > General > Storage, and you will see that the massive grey “System Data” block has completely vanished, instantly restoring gigabytes of usable space.