How to Backup a Mac to an External Hard Drive in 2021

Ben Stockton
By Ben Stockton
— Last Updated: 2019-11-27T09:07:53+00:00

Apple Mac computers might be well built and feature-filled, but buying a Mac doesn’t mean you’re safe from data loss. All good tech can fail, and it’s important to know how to backup a Mac to an external hard drive so that your data is kept safe in a crisis.

Thankfully, there are a few ways to keep your Mac backed up. You can manually copy your files to an external drive, you can use the built-in Time Machine application to sync your files instead or you can save your files with a third-party cloud backup service.

Before you start, remember to avoid some of the common backup mistakes. You’ll also need to make sure you’ve invested in one of the best external hard drives for your Mac.

How to Backup a Mac to an External Hard Drive

If you want to backup your Mac files, the easiest solution is to use Time Machine, but this has some problems, especially if you want to access your files on other devices. Windows PCs, for instance, can’t read the HFS+ file system that Apple uses for drives with Time Machine.

If this isn’t a problem, then feel free to use Time Machine, which we describe in further detail below. Otherwise, use an external hard drive formatted with FAT32 or exFAT file systems. 

A Mac running macOS can read drives formatted with FAT32 or exFAT, as can Windows PCs. A FAT32 drive can only support files up to 4GB in size, so exFAT would be a better alternative. To format your external drive to exFAT or FAT32, open the Disk Utility app. You can access this from the “other” folder in your Apple Launchpad.


If you haven’t formatted your drive yet, macOS will automatically tell you that the drive can’t be recognized. If you see this display box, click “initialize” to automatically open the Disk Utility app instead.


In the left-hand menu of the Disk Utility app, you should see your drive listed under the “external” tab. Click on your drive, then select the “erase” button in the menu at the top.


Give your external drive a suitable name in the “name” text box. In the “format” dropdown menu, select “MS-DOS (FAT)” to format as FAT32, or “ExFAT” to format your drive as exFAT.


If the option is available, select “master boot record” from your “scheme” dropdown menu, then click the “erase” button to begin formatting your drive.


Once your drive is formatted, click “done” and then exit the Disk Utility app. From here, open Finder, the macOS file explorer, then select your external drive from the “locations” tab in the left-hand menu.


You’ll want to open a second Finder window to allow you to easily move files across from your Mac drive to your external hard drive. To do this, right-click on the Finder icon in the dock at the bottom, then click “new finder window” to open a second window.


This isn’t an automated process, so you’ll have to begin moving or copying files from one window to another. The easiest way to do this is to have your external hard drive open in one Finder window while having your important files and folders accessible from the second window.

You’ll need to do this on a regular basis if you want to back up your files. Alternatively, you can use a Mac backup solution that will automatically copy your files to your drive.

How to Backup a Mac to an External Hard Drive

  1. Insert your drive and use the Disk Utility app to format it.
  2. Open two Finder windows. One should show your internal drive, while the other should show your external drive.
  3. Move or copy the files and folders you want to save from your internal drive to your external drive.

How to Check Storage on Mac

Before backing up your files to an external drive, you should check your storage. You can do this from within the Disk Utility app.

From here, you can run the “first aid” process. This will scan your drive for errors and, when possible, automatically fix them for you. You should do this on both your internal Mac hard drive and your external hard drive.


If your macOS can’t fix the errors on your external drive after running the “first aid” process, you should look at replacing it before backing up your files. Choosing the right hard drive brand is important, as some manufacturers are more prone to failure. You should look at buying the most reliable external hard drive for your Mac backups.

In most cases, however, the “first aid” process should complete automatically after a period of time. This may vary, depending on the size of your drive and any potential errors found.


You should also perform this check on your internal drive. If the “first aid” process detects errors, then this might indicate a potential hardware failure with your Mac hard drive. If this is the case, you’ll need to begin immediately backing up your files without delay.

How to Backup Mac

Although backing up your Mac with an external hard drive is sensible, there are alternatives. As our online backup services show, there are several online cloud backup solutions that you can use with your Mac instead.

Cloud solutions offer up to unlimited storage, while also reducing the chances of losing your data. If you keep your external hard drive in the same location as your Mac, you risk losing both if physical damage or loss, like from fire damage or theft, were to occur. 

A cloud solution removes this threat. If you’re backing up to an online provider, such as Backblaze, you’ll gain unlimited data storage (see our Backblaze review). This means you can make an entire copy of your internal Mac hard drive and store it online for you to retrieve.

You could also use a backup service specifically designed to protect you from hardware failures, such as Acronis True Image (see our Acronis True Image review). This solution creates an image backup of your drive and stores it securely in the cloud instead.

Whichever method is your favorite, you shouldn’t rely on a single backup for your Mac. Backing up to an external hard drive and to an online backup service keeps your data safe, whatever happens to your hardware.

Time Machine

We’ve talked through how to manually backup individual files and folders to an external drive, but if you want to back up your entire machine, Apple’s built-in Time Machine is going to be the first option most Mac owners will consider.

Time Machine can create hourly, daily and weekly snapshots of your data, which it then saves to external hard drives or network storage. You can’t sync Time Machine backups to iCloud, Apple’s own cloud storage service, but you can sync your Time Machine backups to the cloud using third-party cloud backup services. 

This depends on the cloud storage provider you choose to use. Services such as Backblaze or Carbonite (see our Carbonite review) support macOS, but you’ll need to set these services to sync your Time Machine backups.

You can set up Time Machine from your System Preferences app, which is likely to be on your app dock. You can also find it from the Launchpad. From here, click on Time Machine.


In the Time Machine settings menu, click the “select backup disk” button. Select your external drive from the menu, then click “use disk” to confirm it as your Time Machine backup drive.

If you’d like to encrypt your Time Machine backups, make sure you click the “encrypt backups” checkbox before you click on the “use disk” button.


Your external hard drive will need to be erased first if it uses a non-Apple file system, such as FAT32, NTFS or exFAT. This means you can’t mix and match a manual backup solution like we’ve described above with Time Machine backups on the same drive. If you want to proceed, click the “erase” button to begin erasing your drive.


Once Time Machine has configured your drive, make sure to click the “back up automatically” checkbox to enable automatic backups. Your external drive will need to remain connected to your Mac for this option to work, though.

The first Time Machine backup will take some time, as it makes a full snapshot of your drive. Future snapshots will only include files that have changed since the last backup, to prevent unnecessary storage use. This means your future Time Machine backups will be a lot quicker to process.

Final Thoughts

Whether you manually copy your files, use Apple’s Time Machine or rely on a cloud backup service, it’s important for you to make regular backups of your important Mac files and folders. We recommend using an external hard drive, especially for large backups, but you should consider combining these with a cloud service in the long term.

Using a 1TB external hard drive is the bare minimum we’d recommend for a long-term Mac backup solution. You can look through our recommendations for the best 1TB external hard drives or look through some of our other hardware articles for alternatives.

Do you use an external hard drive for your Mac backups, or do you prefer cloud storage solutions? Let us know your strategy for Mac backups in the comments below. Thanks for reading.