A Step-by-Step Guide

Formatting a USB drive on macOS is a must and essential for compatibility, performance, and data management. Whether we are preparing a flash drive for cross-platform use, troubleshooting, or erasing sensitive files, macOS offers two primary methods: Disk Utility (visual) and Terminal (command-line).

This article will cover both methods, ensuring you can choose the method of your choice.

Why Format a USB Drive on macOS?

• Compatibility: Ensure seamless file transfers between macOS, Windows, or Linux.
• File System Optimization: Choose the right format (APFS, exFAT, FAT32, etc.) for your needs.
• Data Security: Permanently erase confidential files.
• Error Resolution: Fix corrupted drives or unrecognized storage devices.

Part 1: Formatting a USB Drive Using Disk Utility (Visual Method)

Disk Utility is macOS’s built-in tool for managing storage devices. It’s user-friendly and ideal for those who prefer a graphical interface.

Step 1: Back Up Your Data

Shall be a habit of all sysadmins before formatting, ensure all important files on the USB drive are backed up either on the PC or at an external location e.g. cloud storage.

Note: Formatting erases all data permanently.

Step 2: Open Disk Utility

• Go to Finder > Applications > Utilities > Disk Utility.
• Alternatively, use Spotlight Search (Cmd + Space) and type “Disk Utility.”

Step 3: Select the USB Drive

• In the left sidebar, locate your USB drive under External.
• Click the drive name (e.g., “SanDisk USB”) twice—first select the parent device (usually labeled with the storage size), then the volume below it.

Step 4: Erase the Drive

1. Click Erase in the top toolbar.
2. Configure the settings:

• Name: Assign a new name (e.g., “Backup Drive”).
• Format: Choose a file system:
  • APFS: Optimized for macOS 10.13+ (best for SSDs and internal drives).
  • Mac OS Extended (Journaled): Compatible with older macOS versions.
  • exFAT: Ideal for cross-platform use (Windows and macOS).
  • FAT32: Universal compatibility but limited to files under 4GB.
• Scheme (if available): Select GUID Partition Map for Intel-based Macs or Apple Partition Map for older systems.

1. Click Erase to confirm.

Step 5: Eject the Drive

Once formatting completes, click Eject (⏏) next to the drive name in Disk Utility or Finder.

Tips for Disk Utility:

• Use exFAT if sharing files between macOS and Windows.
• Avoid FAT32 for large files (e.g., videos, disk images).
• If the drive isn’t visible, try a different USB port or restart your Mac.

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Part 2: Formatting a USB Drive Using Terminal (Command-Line Method)

For advanced users, Terminal offers precise control over the formatting process.

Step 1: Identify the USB Drive

1. Open Terminal (Finder > Applications > Utilities > Terminal).
2. Type diskutil list and press Enter.
3. Locate your USB drive in the list (check the size and name, e.g., /dev/disk2).

Step 2: Unmount the Drive

Unmount (but don’t eject) the drive using its identifier:

bash
diskutil unmountDisk /dev/diskX

Replace `diskX` with your drive’s identifier (e.g., `disk2`).  
Step 3: Format the Drive  using the following command

sudo diskutil eraseDisk FILE_SYSTEM NAME DISK_IDENTIFIER

- **FILE_SYSTEM**: Choose from `APFS`, `JHFS+` (Mac OS Extended), `exFAT`, or `FAT32`.  
- **NAME**: The new volume name (e.g., “USB_Drive”).  
- **DISK_IDENTIFIER**: The drive’s identifier (e.g., `disk2`).  

Example Command for exFAT:  

bash
sudo diskutil eraseDisk exfat USB_Drive /dev/disk2

Step 4: Verify the Format
1. diskutil list again to confirm the new file system.
2. Eject the drive safely using:

bash
diskutil eject /dev/diskX

Terminal Tips:

• Use man diskutil to view the manual for advanced commands.
• Double-check the disk identifier to avoid formatting the wrong drive.
• Add -force to bypass confirmation prompts (use with caution).

Choosing the Right File System

• APFS: Best for macOS only SSDs and modern workflows (supports encryption).
• Mac OS Extended (HFS+): Use for Time Machine backups on older macOS versions.
• exFAT: Ideal for large files and cross-platform sharing.
• FAT32: Compatible with game consoles, media players, and older devices.

FAQs About Formatting USB Drives on macOS

1. Will formatting a USB drive delete all data?

Yes. Always back up files before formatting.

2. Why is my USB drive not showing up in Disk Utility?

Try these fixes:

• Reconnect the drive or use a different USB port.
• Restart your Mac.
• Check for hardware damage.

3. Can I recover data after formatting?

Only with third-party recovery tools like Disk Drill, and only if the drive hasn’t been overwritten.

4. How do I format a USB drive to work with Windows?

Use exFAT or FAT32 (if file sizes are under 4GB).

Final Thoughts

Whether you prefer the simplicity of Disk Utility or the flexibility of Terminal, formatting a USB drive on macOS is straightforward. Match the file system to your use case, and always double-check the drive identifier in Terminal to avoid accidental data loss.