Secure disk wipe with Windows format command

April 9, 2021

From Windows 8 Microsoft snuck in a refinement to the format command. It is now possible to get it to do multi-pass random-number disk wipes. From the help (Win 10 20H2):

 /P:count  Zero every sector on the volume. After that, the volume
           will be overwritten "count" times using a different
           random number each time. If "count" is zero, no additional
           overwrites are made after zeroing every sector. This switch
           is ignored when /Q is specified.

So to do a single-pass random wipe:

Repartition disk with one partition (if desired) and give it a drive letter (let’s say F for this example). Probably a good idea to remove any OEM, EFI, recovery partitions like this. A quick way to do this is to use the clean command in diskpart.
Run format F: /P:1
If you feel like it finish up with a clean command in diskpart.

This should do a pass with all zeros, and then a random-number pass.

Note this isn’t a full ‘write random data to every block in the drive’ erase, but should still be secure enough for most purposes.