External drives · Drive formats

How do I reformat an external drive to APFS on a Mac?

Short answer: Back up the drive, open Disk Utility, choose View → Show All Devices, select the drive, click Erase, and pick APFS with GUID Partition Map. Then select it in Storage Studio's Choose Drive.

Use Disk Utility — erasing deletes everything on the drive, so copy off anything you need first.

  1. Open Disk Utility (Applications → Utilities).
  2. Choose View → Show All Devices, then select the drive itself (the top line), not just its volume.
  3. Click Erase.
  4. Give it a name, choose APFS as the format and GUID Partition Map as the scheme.
  5. Click Erase and wait for it to finish.

Then open Storage Studio's Choose Drive (or the setup wizard), select the drive and run the speed test. Storage Studio itself never reformats drives.

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