hard drive - Finding out what directories are using the most space on windows

Hi, I have about 2 terabytes of total space spread over several drives.. While I still have 500 GB free which should last quite a while I want to do some cleanup.

I'm not very organized and the directory structure is a total mess.. It would take days to go through everything, but according to the 80/20 rule 80% of the space is used by 20% of directories. How do I find them?

For example:
C:\a - 200 GB
C:\b - 111 GB

Then if I want to see the subdirectories of C::
C:\a\b - 140 GB
C:\a\aaaa - 100 GB

..and so on.

Is there a builtin windows command / program or a 3rd party utility to do that?

Answer

WinDirStat was made for this task!

It'll show you exactly where your space is going.