Files are stored on the
disk in what is called called
clusters (a group of disk
sectors). Size on disk refers to the amount of cluster allocation a file is
taking up, compared to file size which is an actual
byte
count. The lowest cluster size for
FAT32 is 1, so if
the actual file only needs a small portion of the cluster, the size on disk for
that file will reflect the entire cluster as being used. This is why when you
check the properties tab of a file (using
Microsoft Windows), you will usually see the size on disk size is larger
than the file size.
See also cluster and file.
