Partition a disk with Disk Utility

I want to partition a USB flash drive into 2 ExFAT partitions using Disk Utility. But I find that after formatting the disk as ExFAT, when I click the Partition tab it says "This volume can't be resized." and then the + below the pie chart is greyed out. If I select APFS format (or MacOS Extended) the pie chart can be partitioned, but not for ExFAT or MS-DOS (FAT).

Is it possible to create ExFAT partitions with Disk Utility?

MacBook Pro (2017 – 2020)

Posted on Dec 12, 2023 5:45 PM

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Posted on Dec 12, 2023 8:53 PM

I think I've found a solution to my drive formatting problem.


  1. Erase drive and format as APFS.
  2. In the partition pane, create a new APFS partition. Name this Untitled and reduce to a minimum size.
  3. Create another new APFS partition.
  4. This gives you 2 large partitions. I set each to about 50% of the remaining size, and named them MUSIC and TESLADRIVE.
  5. Once the sizes are set, their format can be changed to ExFAT. Untitled remains as APFS.


It seems Disk Utility doesn't allow the size of ExFAT drives to be changed, which is why they need to be created as APFS.

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Question marked as Top-ranking reply

Dec 12, 2023 8:53 PM in response to brianbron

I think I've found a solution to my drive formatting problem.


  1. Erase drive and format as APFS.
  2. In the partition pane, create a new APFS partition. Name this Untitled and reduce to a minimum size.
  3. Create another new APFS partition.
  4. This gives you 2 large partitions. I set each to about 50% of the remaining size, and named them MUSIC and TESLADRIVE.
  5. Once the sizes are set, their format can be changed to ExFAT. Untitled remains as APFS.


It seems Disk Utility doesn't allow the size of ExFAT drives to be changed, which is why they need to be created as APFS.

Dec 12, 2023 7:22 PM in response to Grant Bennet-Alder

When I first go into the partition pane, it appears to show just one partition, the full size of the drive (in this case 128GB). I've tried moving the edge of that partition pie slice, to try to reduce it, but without success. And the +/- controls below it are greyed out in ExFAT so cannot be used. They can be used for APFS.


I created a smaller partitioned USB drive using a Windows PC, and it works well in the TESLA, but was hoping I could do the same on my Mac for the bigger drive.


I tried creating the partitions in APFS, which I can do, but then they cannot be changed to ExFAT, which the Tesla requires.

Dec 12, 2023 6:57 PM in response to brianbron

It's a little tricky to do what you describe. The partition pane looks static, but has MANY moving parts.


In the Partition pane, you need to click on the particular 'Piece of the pie' partition you initially created, then reduce the size of only that partition, to make space for another partition. You can either drag or use the digital entry below.


Once you have created some blank space, you should be able to add an additional partition, but it may take clicking around to select the blank space, then Create a partition in that space.



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Partition a disk with Disk Utility

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