Mac storage basics · Disks, APFS and formats

How do I erase or format a drive on a Mac?

Short answer: Back up first, open Disk Utility, choose View → Show All Devices, select the drive, click Erase, and choose a format with the GUID Partition Map scheme.

Use Disk Utility, and select the whole device rather than a single volume.

  1. Copy anything you need off the drive — erasing deletes everything on it.
  2. Open Disk Utility and choose View → Show All Devices.
  3. Select the drive itself (the top-level device, not just a volume) and click Erase.
  4. Pick a name, a Format (APFS, Mac OS Extended or exFAT) and Scheme: GUID Partition Map, then click Erase.

Selecting the whole device ensures old partitions are replaced. Never erase your startup disk from inside macOS.

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