How to back up a Mac with Time Machine
Time Machine is the backup tool built into every Mac. Once you point it at an external drive, it copies everything on the Mac, then keeps adding whatever has changed, for as long as the drive is plugged in. This guide sets it up from scratch using a drive connected by cable. It covers macOS Ventura and later, where the settings live in System Settings rather than the older System Preferences.
What you'll need: An external hard drive or SSD with more capacity than the Mac's own storage — Apple suggests at least twice as much. Anything already on the drive will be erased, so use one you can give over to backups entirely.
Plug in the drive
Connect the drive to the Mac and wait for its icon to appear on the desktop or in the Finder sidebar.
Open Time Machine settings
Click the Apple menu () in the top-left corner of the screen and choose System Settings. In the sidebar, click General, then click Time Machine on the right.
Add a backup disk
Click Add Backup Disk…. If you already have a backup disk set up and want to add another, click the + button under the list instead.
Choose the drive
A list of drives the Mac can use appears. Click the one you plugged in, then click Set Up Disk….
Decide whether to encrypt the backup
The next screen has an Encrypt Backup switch, turned on by default. Leave it on. An encrypted backup can't be read by anyone who takes the drive, which matters because the drive holds a copy of everything on your Mac.
Type a password in the New Password and Re-enter Password boxes and add a hint. Then click Done.
Erase the drive if asked
If the drive isn't in a format Time Machine can use, a message explains that it needs to be erased first. Click Erase. This removes everything currently on the drive.
If you are not asked, the drive was already in a suitable format and nothing has been removed.
Let the first backup run
The drive now appears in the Time Machine settings and the first backup starts on its own. A progress bar shows how much is left. This first run copies the whole Mac, so leave the drive connected and the Mac awake and plugged into power until it finishes.
Later backups only copy what has changed since the last one, so they are far smaller and run in the background without you noticing.
Check how often it backs up
Still in Time Machine settings, click Options…. The Back up frequency menu is set to Automatically Every Hour. That is the right choice for most people. You can change it to every day, every week, or Manually if you would rather start each backup yourself. Click Done.
Variations
Open System Settings, click Control Centre in the sidebar, scroll down to Time Machine and set it to Show in Menu Bar. A clock-face icon appears at the top of the screen. Click it to see when the last backup ran, to start one with Back Up Now, or to browse old versions of your files.
In Time Machine settings, click Options…. Under Exclude from Backups, click the + button, choose the folder you want to leave out, and click Exclude. Large folders you can recreate, such as downloaded video or a virtual machine, are the usual candidates. Everything else is worth keeping in.
Repeat steps 3 to 6 with a second drive. Time Machine then takes turns, backing up to whichever drive is connected. Keeping one drive at home and one somewhere else protects you if both the Mac and its drive are lost together, in a fire or a burglary.
Troubleshooting
Check the drive appears in a Finder window first. If it does but Time Machine won't show it, the drive is probably formatted in a way Time Machine can't convert, or it is a disk partition it can't use on its own. Open Disk Utility (in Applications › Utilities), select the drive, click Erase, and choose APFS as the format and GUID Partition Map as the scheme. Then try again from step 3.
Time Machine can only back up while the drive is connected. If you use a laptop and unplug the drive, backups pause and resume when you plug it back in. In the meantime the Mac keeps hourly snapshots on its own storage, so recently changed files can still be recovered. Nothing is wrong, but the drive has to come back eventually or the backup falls out of date.
This is expected. When the drive fills up, Time Machine deletes the oldest backups to make room for new ones and tells you it has done so. Your most recent backup is always complete. If you want to keep history for longer, the only answer is a bigger drive.
Always eject the drive before pulling the cable. Click the eject symbol next to its name in the Finder sidebar, or drag its desktop icon to the Bin, and wait for the icon to disappear. Pulling the cable mid-backup can damage the backup so that it has to start again from scratch.
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