Windows – Checking files on an external drive to whole computer for duplicates

deduplicationexternal hard drivefile managementwindowswindows 7

I'm looking to use an external drive for a new purpose and want to see which, if any, files on it are not already on my main pc.

I've seen comparison programs that can compare folders or one drive to another. (e.g. compare internal drive c to external h) But since the files on the external might be on any of the internal drives I'm wondering if anyone knows of a program or method to compare an external drive to ALL the internal drives on a PC. (e.g compare internal drives c,d,e,f,g to external drive h)

Basically I want to make sure I can safely format the external.

Thanks!

Best Answer

Check out this list of duplicate file detectors. Personally, I use Duplicate Cleaner Free, but read the reviews and take a pick.