How to Set Up a Time Machine Backup on Your Mac

Published ✓ Verified ⏱️ 3 min read July 14, 2025 · by Ryan Bennett

You want automatic, restorable backups of your Mac so a lost file or a dead drive doesn’t become a disaster.

Why: Time Machine is built into macOS. Once you point it at an external or network disk, it backs up everything automatically and lets you go back in time to recover individual files or your whole Mac.

Fix 1: Pick a backup disk and connect it

Time Machine needs a separate disk — not your startup disk. Apple recommends a disk at least twice the storage capacity of your Mac so it has room for history.

You can use:

An external USB-C, USB-A or Thunderbolt drive connected directly to your Mac.
A network-attached storage (NAS) device that supports Time Machine over SMB.
The built-in or external disk of another Mac on your network that’s shared for Time Machine.

Connect the drive (or confirm the network disk is reachable) before the next step.

Fix 2: Add the disk in Time Machine settings

Open Apple menu > System Settings > General > Time Machine.
Click Add Backup Disk (or the Add (+) button).
Select your connected storage device, then click Set Up Disk.
If the disk isn’t already in the right format, your Mac asks to erase it so it can be used for Time Machine — anything on it will be wiped, so move files off first.

Fix 3: Turn on encryption (recommended)

During setup you’ll see an Encrypt Backup option. Turn it on to protect the backup with a password so no one can read your files if the drive is lost or stolen.

You’ll be asked to create a backup password. Save it somewhere safe — you’ll need it to restore files later, and it can’t be recovered if you forget it.

Fix 4: Run the first backup and let it finish

After setup, your Mac starts backing up automatically. To start one immediately, choose Back Up Now from the Time Machine menu in the menu bar (turn the menu-bar icon on from the same Time Machine settings screen if you don’t see it).

The first backup copies everything, so it can take a while — leave the Mac on, awake and plugged in until it completes. After that, Time Machine saves only new and changed files, so later backups are much faster.

Time Machine then keeps:

Hourly backups for the past 24 hours.
Daily backups for the past month.
Weekly backups for all previous months.

The oldest backups are deleted automatically once the disk fills up.

FAQ

Can I keep using my Mac while it backs up? Yes. Time Machine runs in the background. The first backup is just larger, so give it time.

How often does it back up? Automatically on the schedule above. You can change the interval under Time Machine settings > Options > Back up frequency.

Can one disk back up two Macs? Yes, if it has enough space — each Mac keeps its own backups on the same disk.

Sources: Apple Support — Back up your Mac with Time Machine · Apple Support — Backup disks you can use with Time Machine