Ask Ubuntu is a question and answer site for Ubuntu users and developers. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I'd like to know how I can specify the cluster size when using mkdosfs /dev/sdx -F 32. I read somewhere that if you want to format it with a 32kb cluster size, this is the command:

mkdosfs /dev/sdx -s 64 -F 32 -I

But, what if I want to format it with a 64kb cluster size? How can I do it? Can someone explain the proper usage of mkdosfs /dev/sdx -s XX in plain words (I'm not a native english speaker)?

share|improve this question
up vote 3 down vote accepted

I believe the command is:

sudo mkdosfs /dev/sdXX -s 128 -F 32 

Since you want 64KB clusters, and the -s means sectors per cluster so, you need 128 sectors, because 128*512 byes = 64KB, making a cluster.

If you want the whole disk to contain a single partition, you would use -I option. So, the command becomes,

sudo mkdosfs /dev/sdX -s 128 -F 32 -I

Credit goes to this Ubuntu forum thread

share|improve this answer
thanks, this was exactly the info i was looking for, i mean the sectors*bytes thing... – Hairo Sep 18 '12 at 13:40
Note that Windows older versions don't support 64K or larger cluster sizes so if you need cross compatibility you might not want to do this: See – Elder Geek Apr 6 '15 at 17:13

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.