WinDirStat is a disk usage statistics viewer and cleanup tool for Microsoft Windows (all current variants).

WinDirStat reads the whole directory tree once and then presents it in three useful views:

- The directory list, which resembles the tree view of the Windows Explorer but is sorted by file/subtree size

- The treemap, which shows the whole contents of the directory tree straight away

- The extension list, which serves as a legend and shows statistics about the file types

Link to WinDirStat