Jump to content

Welcome to Geeks to Go - Register now for FREE

Geeks To Go is a helpful hub, where thousands of volunteer geeks quickly serve friendly answers and support. Check out the forums and get free advice from the experts. Register now to gain access to all of our features, it's FREE and only takes one minute. Once registered and logged in, you will be able to create topics, post replies to existing threads, give reputation to your fellow members, get your own private messenger, post status updates, manage your profile and so much more.

Create Account How it Works

Format exFat HD - Best Allocation Unit Size for Mac and Win

Format exFat external hard drive portable hard drive allocation unit size Mac Win PC Apple

  • Please log in to reply




  • Member
  • PipPip
  • 17 posts

I'd appreciate anyone's advice or shared experience.


1)  Does anyone know the minimum allocation unit size (AUS) - which I should select when I format an external Hard Drive (HD) to exFat ?


2)  Do I need to do a full format when I format the HD to exFat?  Or, is a quick format okay?



I am currently using PC (Win 7-10) - and I am planning to get a Mac so I want to format my backup HD to exFat.


PC (Win) AUS default = 256 Kb 


Mac AUS default = 128 Kb or 64 Kb (does anyone know?)


I found very few answers when I 'researched' online.  A couple of writers (not Apple reps) wrote that 128 Kb was the minimum for read/write on Mac OS - and thus, 128 Kb should be the AUS.  Another couple of writers (not Apple reps) claimed that 64Kb is the default which will work as the AUS and that even 32Kb or less, should work.  



  • 0


Similar Topics

Also tagged with one or more of these keywords: Format, exFat, external hard drive, portable hard drive, allocation unit size, Mac, Win, PC, Apple

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

As Featured On:

Microsoft Yahoo BBC MSN PC Magazine Washington Post HP