How do I format an external SSD for Mac?

Using an external solid state drive (SSD) is a great way to add fast, portable storage to your Mac. However, before you can start using a new external SSD, you’ll need to properly format it for use with macOS.

Requirements for Formatting an External SSD for Mac

  • External SSD drive
  • Mac computer running macOS 10.12 Sierra or later
  • USB 3.0 or USB-C cable to connect the SSD (usually provided with the drive)

Step 1: Connect the External SSD

Connect the external SSD to your Mac using the provided USB cable. Most external SSDs today use a USB-C or USB 3.0 connection. Plug the cable into one of the USB ports on your Mac.

Step 2: Open Disk Utility

The Disk Utility app is used to manage internal and external storage on your Mac. To open it:

  1. Click on the Finder icon in your Dock
  2. Select Applications > Utilities > Disk Utility

This will open the Disk Utility app.

Step 3: Select the External SSD

You should see your external SSD listed on the left side of the Disk Utility window. Click on it to select it.

Step 4: Click Erase

With your SSD selected, click on the “Erase” button at the top of the Disk Utility window. This will open the erase dialogue.

Step 5: Choose a Format

In the erase dialogue, set the following options:

  • Name – You can leave it as Untitled or enter a name for your SSD
  • Format – Choose APFS
  • Scheme – GUID Partition Map

APFS is the modern file system used by macOS. GUID Partition Map is the required partition scheme.

Step 6: Click Erase

After entering a name and selecting APFS format, click the “Erase” button at the bottom of the dialogue box. This will format the external SSD for use with your Mac.

Step 7: Wait for Formatting to Finish

It may take a few minutes for the formatting process to complete. The SSD will show a status bar that fills from left to right when it is being formatted. When it finishes, you’ll see a message that the erase was successful.

Step 8: Use the External SSD

With formatting complete, your external SSD is now ready to use! The SSD will be available in the Finder and you can start copying files to it.

Some tips for using your new external SSD:

  • For fastest transfer speeds, use a USB 3.0 or USB-C port on your Mac
  • You can create separate partitions if you want to organize files
  • Use Time Machine to backup your Mac to the external SSD

Enjoy having this fast external storage for your Mac! An SSD provides much quicker access to your files compared to traditional hard drives.

Frequently Asked Questions

Why do I need to format the external SSD before using it?

New external SSDs are formatted with a different file system (usually exFAT) optimized for cross-platform compatibility. To work seamlessly with macOS, the drive needs to be reformatted to use the APFS file system your Mac uses.

What format should I use for macOS 10.14 Mojave or earlier?

For older versions of macOS prior to Catalina (10.15), you should format your external SSD as Mac OS Extended (HFS+) instead of APFS. APFS is optimized for newer macOS versions.

How do I partition an external SSD?

In Disk Utility, select your external SSD and click the Partition button. Here you can split the drive into separate partitions, set sizes, name them, and choose formats.

Can I use an external SSD that is already formatted for Windows?

Yes, you can reformat a Windows-formatted external SSD to work with your Mac. Simply follow the steps above to erase and reformat the drive for macOS.

Should I eject an external SSD before disconnecting it?

It’s best practice to always eject an external SSD properly before disconnecting it from your Mac. To do this, click the eject icon next to the drive name in the Finder sidebar or drag it from the desktop to the Trash.


Formatting an external SSD for Mac is a quick process using the Disk Utility app:

  1. Connect the SSD to your Mac
  2. Open Disk Utility
  3. Select the SSD
  4. Click Erase and choose APFS format
  5. Click Erase to confirm and format the drive
  6. The SSD will now show up ready to use in Finder

With a properly formatted SSD, you’ll have fast external storage for your Mac. Remember to eject the SSD before disconnecting it, and enjoy the speed boost over regular hard drives!