How to format a USB drive on Mac

The short answer

Plug in the USB drive, open Disk Utility, select the drive, click Erase, choose a format, and confirm.

Before you format

Formatting deletes everything on the drive, so do this first:

  • Back up files you want to keep
  • Check you selected the right drive (not your Mac’s internal disk)
  • Decide the format based on where you’ll use it:
    • exFAT: Best for Mac + Windows
    • APFS: Best for Mac only (newer systems)
    • Mac OS Extended (Journaled): Older Mac support

Steps to format in Disk Utility

  1. Open Finder > Applications > Utilities > Disk Utility.
  2. In the sidebar, click View > Show All Devices.
  3. Select the USB drive (top-level device, not just a volume).
  4. Click Erase.
  5. Enter a name for the drive.
  6. Pick a Format and leave Scheme as GUID Partition Map (usually best).
  7. Click Erase, then Done.

How to fix it if formatting fails

  • Try a different USB port or cable/adapter.
  • Close apps that may be using the drive.
  • In Disk Utility, click First Aid on the drive, then try Erase again.
  • If still failing, open Terminal and use diskutil list and diskutil eraseDisk only if you’re sure of the disk ID.

Quick check after formatting

  • Unplug and reconnect the USB drive.
  • Copy a small file to confirm it works.
  • Eject safely before removing it.