Have you always wanted to back up your iPhone to an external hard drive or SSD? Have you ever needed to back up your iPhone on your Mac, but realized you’ve only got a 256GB SSD and most of it is already full? Are you tired of iCloud Drive and its monthly subscription being the only backup option?

Keep reading and I’ll show you how to use an external drive connected to your Mac so your iPhone backups always land on the bigger storage device instead of your internal disk.

The key to redirecting your iPhone backups is macOS’s symbolic linking capability. Instead of changing how Finder works, which isn’t possible, we’ll trick it by replacing the default backup folder with a link to your external drive. When your Mac tries to save a backup to ~/Library/Application Support/MobileSync/Backup/, it will seamlessly follow the link to your external HDD or SSD.

PrerequisitesCopy link to section

Before we begin, you’ll need:

  • An external HDD or SSD with enough free space, ideally 2-3x your iPhone’s used storage
  • The drive mounted and accessible from your Mac
  • Your iPhone and its USB cable, if you do not use Wi-Fi sync
  • Administrator access on your Mac

Step-by-Step GuideCopy link to section

1. Prepare Your External DriveCopy link to section

First, create a dedicated folder on your external drive. A typical path might look like this:

"/Volumes/External SSD/iPhone Backups"

or, if your drive has a different name:

"/Volumes/Time Machine/iPhone Backups"

Create this folder manually in Finder, or use the Terminal:

mkdir "/Volumes/External SSD/iPhone Backups"

2. Locate and Move Existing BackupsCopy link to section

Your Mac stores iPhone backups in:

"~/Library/Application Support/MobileSync/Backup"

Open Terminal and check if you have any existing backups:

ls -la "~/Library/Application Support/MobileSync/Backup"

If you see folders with long hexadecimal names, those are your existing backups. Move them to your external drive to preserve them:

mv "~/Library/Application Support/MobileSync/Backup"/* "/Volumes/External SSD/iPhone Backups/"

If you do not care about the old backups, you can skip this step.

3. Remove the Original Backup FolderCopy link to section

Now delete the original Backup folder, not just its contents:

rm -rf "~/Library/Application Support/MobileSync/Backup"

If macOS says you do not have enough privileges, use:

sudo rm -rf "~/Library/Application Support/MobileSync/Backup"

Be careful with this command.

This is the crucial step. The following command creates a link at the original location pointing to your external drive:

ln -s "/Volumes/External SSD/iPhone Backups" "~/Library/Application Support/MobileSync/Backup"

Important notes about the command:

  • ln is the link command
  • The first path is your target, the folder on your external drive
  • The second path is the link name, where macOS expects to find backups
  • Use quotes around paths containing spaces
  • No trailing slash after the target folder name

Check that the link was created correctly:

ls -la "~/Library/Application Support/MobileSync/"

If everything is correct, you should see output like:

lrwxr-xr-x  1 youruser  staff  32 Apr 26 10:30 Backup -> /Volumes/External SSD/iPhone Backups

The l at the beginning of lrwxr-xr-x means it is a symbolic link. Good.

External Drive ConsiderationsCopy link to section

When using a physical external drive, keep these points in mind:

  • Mount persistence: Keep the drive mounted before starting backups
  • Connection stability: Do not unplug the drive while a backup is running
  • Permissions: The drive must be writable by your Mac user
  • Format: APFS or Mac OS Extended is usually the safest choice for a Mac-only backup drive

Apple enables encrypted backups by default, and you should keep this setting. Encrypted backups include saved passwords, Health data, and other sensitive information. The symbolic link works identically for both encrypted and unencrypted backups, because encryption is handled by the iPhone before data reaches your drive.

To verify encryption is enabled:

  1. Connect your iPhone
  2. Open Finder on macOS Catalina or later, or iTunes on older macOS versions
  3. Select your device in the sidebar
  4. Check “Encrypt local backup” under the Backups section

TroubleshootingCopy link to section

“Backup could not be completed” error:

  • Verify the external drive is mounted: ls /Volumes/
  • Check link integrity: readlink "~/Library/Application Support/MobileSync/Backup"
  • Ensure adequate free space on the target drive

Permission denied errors:

  • Run ls -la on your external folder to verify ownership
  • Reconnect the drive if Finder mounted it with unexpected permissions

Backups still appear on internal drive:

  • You may have created the link incorrectly. Delete it with rm "~/Library/Application Support/MobileSync/Backup" and repeat step 4 carefully

Reverting to Default LocationCopy link to section

In case you need to switch back, simply:

rm "~/Library/Application Support/MobileSync/Backup"
mkdir "~/Library/Application Support/MobileSync/Backup"

Then move any backups from your external drive back to the original location.

ConclusionCopy link to section

With this setup, every future iPhone backup will automatically be stored on your external hard drive or SSD, freeing your Mac’s internal storage while keeping your data safe and accessible. This simple symbolic link trick turns your backup workflow into a seamless setup that runs quietly in the background.

No monthly iCloud subscription required and no more worrying about SSD space or manually moving backup files. Your iPhone data flows directly to your chosen external drive, encrypted and intact. Just remember to keep the drive connected before starting backups and occasionally verify that it is still mounted.