Most often USB flash drives on the market are pre-partitioned under (Windows) Master Boot Record.

Until El Capitan a special widget in Disk Utility made it possible to set the partition type to GUID.

In High Sierra there is a dedicated partition button, but it is greyed out. How can an alternative partition table be chosen?

1 Answer 1


In Disk Utility, near the close/minimize/fullscreen buttons, you can see a "View" mode dropdown menu. Set the view mode to "Show All Devices", then you'll see the "root" drives. Click on a root drive, and then click on the "Erase" button. Now an option to change the "Scheme" from Master Boot Record to GUID appears in the Erase subwindow.

  • (Not OP) If I remove the root drive, will the recovery partition be removed as well? Oct 9, 2017 at 2:34
  • 2
    OMG Thank You! I've been struggling with this for an hour and no answer was correct until yours. I had not been seeing the ROOT drive of my USB until I clicked "Show All Devices" like you advised.
    – Kate
    May 31, 2018 at 0:42
  • 9
    This should be default view for disk utility. Really dont understand sacrificing user experience for bauhaus minimalism bullsh*.
    – james-see
    Aug 14, 2018 at 13:02
  • You sir, are a HERO. Dec 23, 2018 at 16:06
  • Didn't understand that there are different setting views in the Diskutil up until now, thank you for this answer @Bruno!
    – jessica
    May 21, 2020 at 12:32

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