I have an external USB hard drive that I'd like to format to UDF for cross-compatibility with Windows and Macs. I tried exFAT, but for whatever reason, because of the block size (56KB) of the format, it's eaten up a huge portion of the disk space (~400GB actual data, ~900GB used disk space).

Is there a utility on Mac OS X to format hard drives to UDF?

I can't find any built-in to my version (OS X 10.8.2), and mkudffs doesn't appear to be in my $PATH, so I'm not sure where to go from here.

  • OS X is supposed to fully support NTFS since Snow Leopard (fully updated), and anything newer. If I were you, I would go with that, unless you use Macs with older OS versions. Sounds simpler.
    – Ariane
    Feb 21, 2013 at 1:15
  • @Ariane It doesn't support writing to NTFS, only reading.
    – Tyilo
    Feb 24, 2013 at 17:43
  • @Tyilo macbreaker.com/2012/02/… Looks like you need a third-party thingie.
    – Ariane
    Feb 24, 2013 at 21:58
  • @Ariane I'm aware of those products, however I wanted to point out that OS X doesn't support NTFS-writing out of the box.
    – Tyilo
    Feb 24, 2013 at 22:04
  • @Tyilo Yeah, sorry. An article I'd read sort of implied that, but looks like I'd interpreted it wrong.
    – Ariane
    Feb 24, 2013 at 22:07

3 Answers 3


Using the Terminal, you might be able to format a disk into UDF. I use the following command to format Blu-Ray-Disks:

newfs_udf -v "Untitled UDF" -r 2.60 /dev/diskX

You might want to first find out under what device name your actual disk is found.

  • 2
    I put it on Github.
    – aross
    Nov 22, 2013 at 14:36
  • 3
    Revision 2.60 of UDF wastes space with an additional partition for metadata. This feature is useful to increase performance for DVD/BD media, but it is useless on hard disk and flash as it will reduce write performance. I recommend to use instead revision 2.01.
    – dolmen
    Jun 2, 2014 at 21:18
  • 1
    Not to mention that revisions > 2.01 supposedly cannot be mounted in read-write on Linux.
    – Tobia
    Oct 18, 2014 at 20:27
  • This works on my M1 MacBook Air running Mac OS 11.1 using a Pioneer BDR-XS07 drive. I can drag and drop files onto the disc from the Finder. Only problem is it is way slower than a flash drive. Mar 31 at 22:01

Someone did some research into how to format a flash drive with udf so it can be used on as many operating systems as possible. His findings are at http://sipa.ulyssis.org/2010/02/filesystems-for-portable-disks/ and there's a script to format the disk properly at http://sipa.ulyssis.org/wp-content/uploads/2010/02/udfhd.pl_.txt

  • is there an utility for windows to format a drive in udf like the perl script does? Mar 21, 2014 at 21:14

following project works just fine formatting any removable drive with UDF:


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