WinDirStat

If you want to get a quick overview of where data is stored on a hard drive or network directory, and what types of files are present, try the free utility, WinDirStat, available at: https://windirstat.net/ .

As you can in this screen grab, WinDirStat shows the percentage of a drive's data that individual folders hold. So the 'My Documents' folder has 79.5% per cent of the data on the C drive, and the 'My Music' subfolder has 88.2% of the data in that 'My Documents' folder.

The graphic at the bottom of the screen shows at a glance that by far MPEGs are the most common file type on the C drive, by referring the color code list on the upper right.