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How do I check the cluster/allocation size of an exFAT drive on Windows?

phuclv
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woojoo666
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3 Answers3

30

You can use wmic (now deprecated)

C:\>wmic volume get driveletter,blocksize
BlockSize  DriveLetter
4096       D:
4096       C:

In PowerShell you'll have various other solutions like below

PS C:\> (Get-Volume C).AllocationUnitSize
4096
PS C:\> (Get-WmiObject win32_volume | where { $_.driveletter -eq 'C:' }).BlockSize
4096
PS C:\> (Get-CimInstance win32_volume | where { $_.DriveLetter -eq 'C:' }).BlockSize
4096

Get-WmiObject is deprecated just like wmic, so Get-CimInstance is better going forward

Alternatively you can also run fsutil fsinfo ntfsInfo drive: as admin to get more detailed information, or use fsutil fsinfo ntfsInfo <drive> | findstr /c:"Bytes Per Cluster" to get just the cluster size.
Update: unfortunately ntfsInfo (and refsInfo) only work for the corresponding filesystems, not exFAT

phuclv
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2
  1. One option is chkdsk:

use chkdsk to get cluster size

  1. Create 1 byte text file, then look at properties of the file to see how much space on disk occupies -> that's your cluster size!

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0

Right-click the drive and click "format", and the pop-up window will show the current cluster size under "allocation unit size". Be careful that you don't actually format the disk though!

woojoo666
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