How to Use the Mac Disk Utility to Format a USB Drive

Whether you just bought a brand new flash drive or you want to completely wipe an old one to start fresh, you need to format it. On a Mac, formatting a drive is handled by a built-in application called Disk Utility.

The process is incredibly fast, but choosing the correct file system format is crucial. If you choose the wrong one, the drive might work perfectly on your Mac, but be completely unreadable if you plug it into a Windows PC.

How to Erase and Format the Drive

Warning: Formatting a drive permanently deletes every single file on it. Before you begin, verify that there is nothing important on the USB drive.

1. Plug the USB drive into your Mac.
2. Open Spotlight Search by pressing Command + Space on your keyboard.
3. Type Disk Utility and press Enter to open the app.
4. In the left-hand sidebar of Disk Utility, look for your USB drive under the “External” section. (It will often be named the brand of the drive, like “SanDisk” or “Kingston,” or just “Untitled”).
5. Click exactly once on the name of the USB drive to select it.
6. At the top of the Disk Utility window, click the Erase button.

Choosing the Right Format

A pop-up window will appear asking you for three things: a Name, a Format, and a Scheme. The “Format” drop-down menu is the most important decision you will make.

Click the Format drop-down menu and choose one of the following based on your needs:

• ExFAT: This is the best overall choice. An ExFAT drive can be read and written to by both Mac computers and Windows PCs. Choose this if you ever plan to share files with a Windows user.
• Mac OS Extended (Journaled): Choose this only if you intend to use the USB drive exclusively with older Macs, or if you plan to use it as a Time Machine backup drive. A Windows PC will not be able to read this drive.
• APFS: Choose this only for high-speed Solid State Drives (SSDs) being used exclusively with modern Macs running macOS 10.13 or later. Do not use this for standard, cheap USB thumb drives.

Finishing the Process

1. Type a new Name for the drive (e.g., “Work Files” or “Photos”).
2. Ensure the Scheme is set to GUID Partition Map. (If you don’t see a Scheme option, don’t worry, Disk Utility will handle it automatically).
3. Click the red Erase button.

The Mac will spend a few seconds wiping the drive and rebuilding the file system. Once you see the green checkmark saying the process was successful, click Done. Your USB drive is now perfectly formatted and ready to safely store your files.