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APFS, exFAT or Mac OS Extended: which format to use for a drive

· 6 min read

APFS vs exFAT comes down to who reads the drive. Use APFS for a drive that only Macs will use, and exFAT for one that has to work on both a Mac and a Windows PC. Mac OS Extended (Journaled) is only for a Mac running macOS 10.12 or earlier. The format also decides how well the drive copes with being unplugged at the wrong moment, and changing it later usually means erasing, so choose before you copy anything onto it.

Which format for which job

  • Only Macs, any recent macOS: APFS. Choose APFS (Encrypted) if the drive could be lost and holds anything private.
  • Time Machine: APFS. Apple calls APFS or APFS Encrypted the preferred format for a backup disk, and if you pick a disk in another format, Time Machine offers to erase it for you.
  • A Mac and a Windows PC: exFAT, which Disk Utility lists as ExFAT. Apple’s guide says to use it for Windows volumes over 32 GB.
  • A Mac on macOS 10.12 or earlier: Mac OS Extended (Journaled). Apple says APFS is the file system for macOS 10.13 or later, and Mac OS Extended is for compatibility with older versions.
  • A device that insists on FAT32 (some cameras, car stereos and game consoles): MS-DOS (FAT). Apple says to use it for Windows volumes of 32 GB or less, and a single file on it can’t reach 4 GB.

What each one gives up

APFS is the default file system for Macs on macOS 10.13 or later, with encryption, snapshots and space shared between volumes. Windows doesn’t read it without extra software, so don’t use it for a drive you hand to a Windows user. Windows may offer to format a drive it can’t read; decline, because formatting erases it.

Mac OS Extended (Journaled) is the older Mac format. Apple describes it as using a journal to protect the integrity of the file system, so it copes better with a sudden unplug than a format with no journal. On a Mac running 10.13 or later it has no advantage over APFS, and Windows can’t read it without extra software either. Avoid the encrypted version for anything new: Apple says macOS 28 and later won’t support encrypted Mac OS Extended volumes, and recommends APFS (Encrypted) instead. Apple’s Disk Utility guide for macOS 26 and later no longer lists Mac OS Extended among its formats, although the macOS 15 guide still does.

exFAT works on macOS and Windows without extra software, and a single file can be far larger than 4 GB. Microsoft’s own comparison of its file systems lists what it gives up: no journaling, no file owner or permissions, and no encryption. Without a journal, an exFAT drive pulled out without ejecting is more likely to need First Aid afterward, and Disk Not Ejected Properly explains what is at risk. It also has none of APFS’s snapshots.

MS-DOS (FAT) is Disk Utility’s name for the FAT family, which includes FAT32, and older devices are most likely to accept it. Microsoft gives its maximum file size as 4 GB, which a single video file passes quickly. The message Finder shows when you hit that limit is covered in this guide to files too large for the volume’s format.

NTFS is Windows’ own format, and Disk Utility can’t create it. A Mac reads an NTFS drive but can’t write to it without extra software.

Hard drive or SSD

Apple says APFS is optimized for the flash storage in recent Macs, and that it can also be used with traditional hard disk drives and external drives. So a spinning drive doesn’t rule APFS out, and for a drive that only Macs will use it’s the sensible default either way. If the drive holds anything private, encrypting a USB stick or external drive walks through the encrypted option. If you haven’t bought the drive yet, external SSD or an internal upgrade compares the choices.

How to erase a drive and choose the format

Erasing deletes everything on the drive. Copy anything you want to keep to another disk first, and check that the copy opens.

  1. Open Disk Utility from Applications, then Utilities.
  2. Choose View, then Show All Devices.
  3. In the sidebar, select the device itself (the top entry for the drive), not the volume indented under it, and click Erase.
  4. Choose GUID Partition Map from the Scheme pop-up menu. If the Scheme menu is missing, you’ve selected the volume instead of the device.
  5. Pick the Format, such as APFS, APFS (Encrypted), ExFAT or MS-DOS (FAT). The exact list depends on the macOS version.
  6. Give the drive a name and click Erase, then Done. For a Windows format, Apple’s guide gives 11 characters as the longest name.

Some older devices, such as some cameras and car stereos, may expect the Master Boot Record scheme instead of GUID Partition Map. If yours doesn’t recognize the drive, check its manual and erase again with the scheme it asks for.

The Security Options button, when it appears, controls how many times erased data is overwritten. Apple notes that these options aren’t available for SSDs.

Converting instead of erasing

There is one change you can make without erasing. Disk Utility can convert a Mac OS Extended volume on an external drive to APFS: select the volume, choose Edit, then Convert to APFS, and click Convert. Disk Utility warns that APFS volumes can’t be used with older versions of macOS and that you can’t undo the change. It refuses for startup disks, volumes on internal storage and Time Machine backup disks. Back up the drive before you convert it.

Going the other way, from APFS back to Mac OS Extended, or to or from exFAT, means erasing the drive and copying your files back.

Mistakes to avoid

  • Erasing the wrong disk. Read the name and size in the sidebar twice before you click Erase.
  • Using exFAT for Time Machine. Time Machine can’t back up to a Windows-format disk as it is. When you choose one in Time Machine settings, macOS asks whether to erase it so it can be used for Time Machine, and a backup to the wrong format fails with “The backup disk is not in Apple File System or Mac OS Extended (Journaled) format.”

Questions

Is APFS or exFAT better for an external SSD? It depends on which computers use the drive. For Macs only, APFS: it keeps Mac permissions and snapshots and has an encrypted option. For a drive shared with Windows, exFAT, which gives up journaling and permissions in return for working on both.

Can Windows read an APFS drive? Not without extra software. Windows reads and writes exFAT and FAT32 directly, so use exFAT for any drive you move between a Mac and a PC. If Windows offers to format a Mac drive it can’t read, decline, or it erases the drive.

What is the best format for an external hard drive on a Mac? APFS if only Macs on macOS 10.13 or later use it, and Mac OS Extended (Journaled) if an older Mac has to read it. Use exFAT when the drive must work on Windows too.

Can I change a drive’s format without erasing it? Only in one direction: Disk Utility can convert a Mac OS Extended volume on an external drive to APFS, and the change can’t be undone. Every other change, including to or from exFAT, means erasing the drive and copying files back from a backup.