How to format a USB drive on Mac

Complete guide with multiple methods and troubleshooting.

7-10 min read
Expert Verified
Last Updated: August 2025

Quick Answer

Formatting a USB drive on a Mac can be accomplished through various methods, primarily using Disk Utility or the Terminal. This process allows users to erase and prepare the USB drive for new data or to change its file system format.

Beginner/Intermediate⏱ 7-10 min read

Prerequisites & Requirements

Before formatting a USB drive on a Mac, ensure you have the following:
  • •A Mac running macOS (versions 10.12 Sierra and later are recommended).
  • •Administrator access to the Mac.
  • •A USB drive connected to the Mac.
  • •Backup any important data on the USB drive, as formatting will erase all data.

Method 1: Using Disk Utility

Disk Utility is the primary tool for managing disks and drives on macOS. This method is user-friendly and suitable for most users.
  • •Step 1: Open Disk Utility by clicking on the Finder, then selecting 'Applications' > 'Utilities' > 'Disk Utility'. Alternatively, use Spotlight Search by pressing Command (⌘) + Space and typing 'Disk Utility'.
  • •Step 2: In Disk Utility, locate your USB drive in the left sidebar. It may be listed under 'External'. Click on it to select.
  • •Step 3: Click the 'Erase' button located at the top of the Disk Utility window.
  • •Step 4: In the dialog that appears, choose a name for your USB drive, select a format (e.g., 'Mac OS Extended (Journaled)', 'exFAT' for cross-platform compatibility, or 'MS-DOS (FAT)' for older systems), and select a scheme (usually 'GUID Partition Map').
  • •Step 5: Click 'Erase' to begin the formatting process. Wait for the process to complete, which may take a few moments.
  • •Step 6: Once completed, a confirmation message will appear. Click 'Done' to finish.
  • •Step 7: Verify the drive is formatted by checking its format in Disk Utility.

For macOS Monterey (12) and later

The Disk Utility interface has been slightly redesigned in Monterey and later versions.
  • •Step 1: Open Disk Utility as described above.
  • •Step 2: Click on the 'View' button in the upper left corner and select 'Show All Devices' to see your USB drive.
  • •Step 3: Follow the same steps to erase and format the drive as outlined above.

For macOS Big Sur (11) and earlier

The steps remain largely the same, but the interface may look slightly different.
  • •Step 1: Open Disk Utility.
  • •Step 2: Select your USB drive from the sidebar.
  • •Step 3: Click 'Erase' and follow the prompts to format the drive.

Method 2: Using Terminal

For advanced users, formatting a USB drive can also be done through the Terminal, providing more control over the process.
  • •Step 1: Open Terminal by navigating to 'Applications' > 'Utilities' > 'Terminal'.
  • •Step 2: Type the command 'diskutil list' and press Enter to view all connected drives. Identify your USB drive by its size and note its identifier (e.g., disk2).
  • •Step 3: Unmount the drive using the command 'diskutil unmountDisk /dev/disk2' (replace 'disk2' with your drive's identifier).
  • •Step 4: Format the drive with the command 'diskutil eraseDisk exFAT MyUSB /dev/disk2' (replace 'MyUSB' with your desired name and 'disk2' with your identifier).
  • •Step 5: Wait for the process to complete. You will receive a confirmation message in the Terminal.
  • •Step 6: Verify the format by using 'diskutil list' again.

Troubleshooting Common Issues

If you encounter issues while formatting your USB drive, consider the following solutions:
  • •Error: 'Could not unmount disk' - Solution: Ensure no applications are using the drive. Close any open files or applications that may be accessing it.
  • •Issue: 'Erase process has failed' - Fix: Try using Terminal to unmount and format the drive as described in Method 2.
  • •Problem: USB drive not appearing in Disk Utility - Workaround: Check if the USB drive is properly connected, try a different USB port, or restart your Mac.

Advanced Tips & Shortcuts

Here are some tips and shortcuts to enhance your experience:
  • •Keyboard shortcut: Command (⌘) + Space - Opens Spotlight Search for quick access to Disk Utility.
  • •Command line: 'diskutil list' - Lists all connected drives for easy identification.
  • •Hidden feature: Use 'diskutil info /dev/disk2' to get detailed information about your USB drive.

Common Mistakes to Avoid

Avoid these common pitfalls:

Expert Tips

For most users, using Disk Utility is the simplest and safest method to format a USB drive, while Terminal provides advanced options for those comfortable with command-line interfaces.