How to Back Up a Mac with Time Machine

September 11, 2026

Set up Time Machine on an external drive so your Mac backs itself up automatically, then adjust what it excludes and how often it runs.

Time Machine keeps hourly backups of your Mac on an external drive and lets you recover older versions of files or restore a whole Mac. You need a drive with at least as much space as the data on the Mac, ideally twice as much.

Plug in an external drive

Connect a USB or Thunderbolt drive to the Mac. If the drive is new, macOS may ask whether you want to use it with Time Machine. Accept the offer if it does, or continue with the steps below.

Open Time Machine settings

Choose Apple menu, System Settings, General, Time Machine.

Add the drive as a backup disk

Click Add Backup Disk, select the drive in the list, and click Set Up Disk. If the drive is not formatted for Time Machine, macOS asks to erase it. Erasing deletes everything on the drive, so copy off anything you need first. A sheet then lets you turn on Encrypt Backup and set a password, which is worth doing for a portable drive. Click Done.

Let the first backup finish

The first backup copies everything and can take several hours over USB. Keep working; it runs in the background. Click the Time Machine icon in the menu bar to see progress. Later backups copy only what changed and usually finish in minutes.

Adjust exclusions and frequency

Back in System Settings, General, Time Machine, click Options. Under Exclude from Backups, click + and add folders you do not need, such as a virtual machine folder or a cache-heavy project directory. The Back up frequency menu offers Automatically Every Hour, Automatically Every Day, Automatically Every Week, or Manually. Hourly is the default and the safest choice.

If you unplug the drive. Time Machine skips backups until the drive is connected again, then catches up. Leave it plugged in whenever the Mac is at a desk. A network drive or a shared folder on another Mac also works as a destination.

If you need to restore something. Open the Time Machine app from the Applications folder or by searching in Spotlight, browse back in time to the file you want, and click Restore. To move everything onto a new or erased Mac, use Migration Assistant in Applications, Utilities and choose the Time Machine drive as the source.