Setting Up a New Mac from Your Backup: How Migration Assistant Works
Set up a new or replacement Mac from your backup with Migration Assistant. Time Machine and Mac-to-Mac transfers explained step by step.
Whether you’ve just bought a new Mac, your old one has died, or it’s been lost or stolen, getting back to a working setup doesn’t mean starting from scratch. Migration Assistant, built into every Mac, can bring your apps, files, accounts and most of your settings across in one go, whether you’re restoring from a Time Machine backup or transferring directly from another Mac.
What Migration Assistant actually transfers
Migration Assistant moves your user accounts, documents, photos, music, many apps and most settings to the new Mac. It can also bring across Wi-Fi details and iCloud Keychain passwords. Some apps may reset or ask you to sign in again, especially if they are not fully compatible with the new version of macOS.
One thing it never does: transfer macOS itself. Your new Mac keeps whatever macOS version it came with, which is actually the right behaviour, you get your content back without inheriting an outdated operating system.
Scenario 1: setting up a brand-new Mac from a Time Machine backup
This is the most common situation, a new Mac, and an existing Time Machine backup of your old one.
- Make sure your Time Machine backup disk is connected to the new Mac and turned on.
- If your new Mac starts up to the initial setup assistant (asking for your country, network, and so on), migration is already built into that process, just continue through it.
- If you’ve already completed initial setup, open Migration Assistant directly from Applications > Utilities, or find it with Spotlight.
- Enter your administrator password if asked.
- When asked how you want to transfer your information, choose the option to transfer from a Mac, Time Machine, or startup disk, then click Continue.
- Select your Time Machine backup disk, then Continue. It may take a few moments to appear.
- Select a backup (usually the most recent one) and click Continue.
- Migration Assistant will calculate how much space everything will take, this can take a few minutes for a large backup.
- Choose which categories of files you want to bring across, user accounts, applications, and so on, or expand each category to pick specific items. Click Continue when you’re ready.
- If you’re transferring an administrator account, you’ll be asked to set a password for it there and then, make sure you remember it. If you’re transferring a standard account, a temporary password appears on screen, write it down, the user will need it to log in for the first time.
Large transfers can take hours. If you’re moving a lot of data, it’s worth starting the process in the evening and letting it run overnight.
Scenario 2: transferring directly from your old Mac (no backup needed)
If your old Mac still works, you can skip the backup step entirely and transfer directly between the two machines, either over Wi-Fi or with a cable for a faster transfer.
On your new Mac, open Migration Assistant and choose to transfer from a Mac, Time Machine, or startup disk. On your old Mac, open Migration Assistant too, and choose to transfer to another Mac. Your new Mac will then ask you to select the old Mac from the list, and if a security code appears, just confirm it matches on both machines before continuing. From there, the process is the same as above: Migration Assistant calculates the space required, you choose what to bring across, and the transfer begins.
A direct cable connection (Thunderbolt, where available) is noticeably faster than Wi-Fi for large transfers, worth considering if you’re moving a lot of photos or video.
If your old Mac won’t start up at all
This is an important distinction the simple version of this process doesn’t cover: if your Mac won’t start normally, shows a flashing question mark, or needs its operating system reinstalled, Migration Assistant can’t help until macOS itself is reinstalled first, it doesn’t restore the operating system, only your content. In that situation, macOS needs to be reinstalled via macOS Recovery (hold the power button on Apple Silicon Macs, or Command-R on Intel Macs, during startup) before you can migrate anything back from your backup.
What to check after migrating
Once the transfer finishes, a few things are worth checking before you consider the job done. Some apps may need to be reinstalled or re-authorised with a licence key, particularly older software.
Check that you’re properly signed into iCloud and any other account-based services, some passwords sync automatically through Keychain, but not everything does. If you’ve moved from an Intel Mac to Apple Silicon, consider whether any transferred apps should actually be reinstalled fresh rather than carried over, since a fresh native install often runs better than an older version running through Rosetta translation.
Replacing data vs merging accounts
If an account with the same name already exists on the new Mac, Migration Assistant will ask what you’d like to do: replace the existing account with the one from your backup (keeping a copy of the old data if you choose), or rename the incoming account so both exist side by side with separate logins. Worth deciding this deliberately rather than accepting the default, especially if the new Mac already has files on it you want to keep.
Why this matters more than people expect
A lot of people assume setting up a new Mac means starting over, reinstalling every app one at a time, manually copying files across, and reconfiguring settings from memory. Migration Assistant exists precisely so that doesn’t need to happen. Combined with a tested Time Machine backup (see our main guide on backing up your Mac), a new Mac can feel like your old one within an hour or two of opening the box, not a weekend project.
Need help with a new Mac setup or a backup emergency?
Whether you’ve just bought a new Mac, you’re dealing with one that’s died unexpectedly, or you simply want to make sure your next migration goes smoothly, Your Mac Tech can help with the whole process, including making sure your backup is actually restorable before you need it. See our Mac Support & Setup page for more on how we help with new Mac setups, or get in touch directly.
