The Space Files Take
On a folder line this is the total disc space all the files in the folder and all sub-folders take. A file uses a number of disc clusters to save its data, the minimum disc space a file can use is one disc cluster. The size of a disc cluster is dependant on the size of the disc for FAT16 formatted discs and on discs over 1gb is 32Kb, for FAT32 formatted discs a cluster is 4Kb. Even if a file only requires one byte it uses one cluster which could mean it is using 32Kb of disc space to save one byte. WHATSGone works out how many clusters a file is using and can then report the actual amount of disc space used by all the files in the folder.
On a file type line this is the disc space used by all the files of this type in the folder that this file type is a sub-item of.
Note If the disc or folder is compressed then this is the space the file would take if the disc or folder was not compressed. You may find this useful in showing how well compression is working.