Erase and Format a Drive in Disk Utility: APFS vs ExFAT

You want to erase an external drive on your Mac and pick the right format — APFS for Mac, or ExFAT so Windows can read it too.

Why: The format decides which systems can use the drive. APFS is built for macOS and isn’t readable by Windows out of the box; ExFAT works on both Mac and Windows and handles large files and drives. Disk Utility lets you choose the format while erasing.

Fix 1: Choose the right format first

• APFS — use for Mac-only data volumes on macOS High Sierra 10.13 or later. Variants include APFS (Encrypted) and case-sensitive formats; choose a case-sensitive format only when your apps require it.
• Time Machine backup disks — an APFS backup destination requires macOS Big Sur 11 or later. For High Sierra through Catalina, use Mac OS Extended (Journaled) for the backup destination, even if the Mac’s internal disk is APFS. Do not erase an existing working backup disk just to change its format: erasure permanently deletes its backup history.
• ExFAT — use for drives shared with Windows that are over 32 GB (almost all external drives today).
• MS-DOS (FAT) — use for Windows-compatible drives that are 32 GB or less.

Fix 2: Erase and format the drive

Erasing the whole device permanently deletes every volume and file on it, including any backups. Copy anything you need to a different device and verify the copy first. Confirm the selected drive’s name and capacity; do not select your startup disk or another drive by mistake.

1. Open Disk Utility (Applications > Utilities > Disk Utility, or search with Spotlight).
2. Choose View > Show All Devices so you can select the whole device, not just a volume.
3. In the sidebar, select the device (the top-level entry for the drive, not the indented volume under it).
4. Click Erase in the toolbar.
5. Enter a Name.
6. Click the Format pop-up and choose APFS, Mac OS Extended (Journaled) or ExFAT for your intended use and macOS version (see Fix 1).
7. Click the Scheme pop-up and choose GUID Partition Map.
8. Click Erase, then click Done.

Fix 3: Format specifically for Windows

If the drive must work on a PC too:

1. Follow Fix 2, but at the Format step choose ExFAT (over 32 GB) or MS-DOS (FAT) (32 GB or less).
2. Use GUID Partition Map for the scheme for general use; some older PCs expect Master Boot Record — choose that only if the PC won’t read the drive.
3. Keep the volume name short (MS-DOS FAT allows up to 11 characters).

FAQ

Can Windows read an APFS drive? Not without extra software. If you need both Mac and Windows to read and write the drive, use ExFAT.

Should I encrypt it? Choose APFS (Encrypted) for a Mac-only drive holding sensitive data. Don’t encrypt a drive you’ll use on Windows — Windows can’t read APFS encryption.

Sources: Apple Support — Erase and reformat a storage device in Disk Utility on Mac · Apple Support — File system formats available in Disk Utility on Mac · Apple Support — Format a disk for Windows computers in Disk Utility on Mac · Apple Support — APFS Time Machine backup disks · Apple Support — Time Machine disk formats in Catalina