Exclude files from a Time Machine backup on Mac
You can exclude items from a backup to save space on your backup disk, or to exclude items you back up using another method.
On your Mac, choose Apple menu > System Preferences, then click Time Machine.
Click the Add button , then select one or more items to add to the list of excluded items. You can also drag items to the list.
To remove an item, select it in the list, then click the Remove button .
The backup disk is automatically included in the list of items that shouldn’t be backed up.
Excluded items still appear in Time Machine local snapshots.
Note: Although you can choose to exclude system files and apps, it’s not recommended because you can’t use Time Machine to restore your system if your startup disk is damaged. Instead you must reinstall macOS on your Mac, then use Migration Assistant to transfer information from a Time Machine backup or other storage device.