How to Format an External Storage Drive in macOS

Formatting an external drive on your Mac is a straightforward process that lets you choose the perfect file system for your needs—whether you’re backing up with Time Machine, sharing files with Windows PCs, or just clearing a drive for fresh use. Follow these steps to format an external HDD, SSD, or USB flash drive in macOS.

1. Back Up Any Important Data

Why it matters: Formatting erases all data on the drive.

1. Connect the drive to your Mac.
2. Copy any files you need to your Mac’s internal storage or another drive.
3. Double-check the backup before proceeding.

2. Open Disk Utility

1. Click the Finder icon in your Dock.
2. Navigate to Applications > Utilities > Disk Utility, or press Command (⌘) + Space and type “Disk Utility.”
3. Launch Disk Utility.

3. Select the Drive to Format

1. In Disk Utility’s sidebar, locate your external drive under External.
2. Click on the parent drive (the top-level entry, not just a volume or partition).

Tip: If you only see volumes and not the drive itself, click View in the toolbar and choose Show All Devices.

4. Click “Erase”

1. With the drive selected, click the Erase button in the toolbar.
2. A dialog will appear with formatting options.

5. Choose a Name, Format, and Scheme

• Name: Give your drive a simple, memorable name (e.g., “BackupDrive”).
• Format:
  • APFS (Apple File System) – Best for SSDs and macOS 10.13 or later.
  • Mac OS Extended (Journaled) – Ideal for HDDs or if you need compatibility with macOS versions before 10.13.
  • exFAT – Choose if you need to share large files with Windows or Linux.
• Scheme:
  • GUID Partition Map – Required for Intel- or Apple Silicon-based Macs.
  • Master Boot Record – For Windows compatibility only (rarely needed).
  • Apple Partition Map – Only for very old PowerPC Macs.

Pro Tip: If you plan to use Time Machine for backups, select Mac OS Extended (Journaled) with GUID Partition Map.

6. Format the Drive

1. After configuring Name, Format, and Scheme, click Erase.
2. Wait a few seconds while macOS formats the drive.
3. When it’s done, you’ll see a confirmation message—click Done.

7. Verify and Eject

1. Ensure the newly formatted volume appears in Disk Utility and on your Desktop.
2. Before disconnecting, right-click the drive’s icon on your Desktop or in Finder’s sidebar and choose Eject.
3. Once the icon disappears, safely unplug your drive.

Troubleshooting Tips

• Drive Not Showing Up?
  • Try a different USB port or cable.
  • Check System Information (Apple menu > About This Mac > System Report > USB) to see if the Mac detects the hardware.
• Format Fails or Hangs?
  • Run First Aid in Disk Utility to repair errors, then try Erase again.
  • If errors persist, consider using a third-party tool like GParted (via a Linux live USB) to re-partition.

Wrapping Up

Formatting an external drive in macOS is quick once you know which options to choose. Always back up important data first, pick the right file system for your workflow, and use GUID partitioning for modern Macs. With your drive freshly formatted, you’re ready to store backups, transfer files, or repurpose the device entirely.

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Mark Vincent

Tech enthusiast and content creator passionate about making technology simple for everyone. I share practical tips, guides, and reviews on the latest in computers, software, and gadgets. Let’s explore the digital world together!