Directory Size Calculator is an Open Source app to determine how much space is being used in any folder you choose.

The app is portable, so all you need to do is execute DirectorySize.exe and if you no longer need it, simply delete the folder.

Directory Size Calculator does not just randomly search your drive; instead, you need to "Create Directory Tree," in other words, choose the root folder you want to view. You can choose individual folders, and the subfolders will be included or even your entire C: drive. Even browsing my entire C: drive was super fast to get all the information. It loaded my entire C: drive in VMWare in seconds.

Directory Size Calculator will then show you the space used, and the percentage of space used, of the currently viewed folder or file giving you two different ways to analyze space wasted. You can then expand down further into subfolders finally arriving at the exact filenames and space they are using within that folder.

You can now right-click on any folder or file for options.

If you right-click on a folder you can explore the directory, choose as the root directory, explore XML document, move a directory to, delete directory and properties. There are a few additional sub choices in there as well.

If you right-click on any file, you can show it in Explorer, execute it, move it, delete it or get properties.

Directory Size Calculator is a great app if you want to find how much space is being wasted on your hard drive.