When I use Disk Utility app in macOS Mojave to format an external drive, I do not see the new Apple File System (APFS) offered as a choice of format.

Does it matter that my external drive is a Toshiba Canvio® Advance Portable External Hard Drive plugged into a MacBook Pro Retina (late 2013) via USB-3 cable? I know APFS is optimized for solid-state storage, so does Disk Utility not offer it for a spinning-metal disk drive?

➥ Why is APFS not offered by Disk Utility?


Disk Utility will only offer APFS if Partition Map is "GUID Partition Map".


If the Partition Map is "Master Boot Record" APFS is not an option (and neither is encrypted HFS).




The problem is, that DiskUtil only shows you the Volumes on already partitioned disks. Just select View -> Show all devices. Now instead of the Volume select the device you want to partition and APFS and GUID will be offered.

I was able to get the APFS and GUID scheme option by deleting the MBR

  1. Open a Terminal
  2. Find out which disk is your target: diskutil list
  3. Unmount the disk: diskutil umountDisk /dev/disk# with # being the number of the drive you determined in step 1 (e.g. /dev/disk2)
  4. Delete the MBR: dd if=/dev/zero of=/dev/disk# bs=512 count=1

If you open DiskUtil now you will be offered APFS


  • Be aware that you are deleting all partitions from the drive
  • Be careful when selecting the disk
  • This isn't really correct. On GPT formatted disks the first 512 bytes (that you overwrite) contains only the protective MBR which is a pseudo MBR partition table with one partition covering the whole disk. It does not contain the GPT partition table which is in LBA 2 or 3 (see Wikipedia). Perhaps you had a hybrid MBR in which case you have just converted it to an unsafe GPT (i.e. one without protective MBR). Most likely you just had a MBR disk and removed it's partitions. – lx07 Sep 6 at 16:35
  • Thanks for downvoting, but if OP had GPT there would have been no need to delete it in the first place ;) – johnson Sep 23 at 18:45

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