debian man page for isosize

ISOSIZE(8)						       System Administration							ISOSIZE(8)

NAME
       isosize - output the length of an iso9660 filesystem

SYNOPSIS
       isosize [options] iso9660_image_file

DESCRIPTION
       This  command  outputs the length of an iso9660 file system that is contained in the given file.  That file may be a normal file or a block
       device (e.g. /dev/hdd or /dev/sr0).  In the absence of any switches (and errors) it will output the  size  of  the  iso9660  filesystem	in
       bytes.  This can now be a large number (>> 4 GB).

OPTIONS
       -x, --sectors
	      Show the block count and block size in human-readable form.  The output uses the term "sectors" for "blocks".

       -d, --divisor number
	      Only has an effect when -x is not given.	The value shown (if no errors) is the iso9660 file size in bytes divided by number.  So if
	      number is the block size then the shown value will be the block count.

       The size of the file (or block device) holding an iso9660 filesystem can be marginally larger than the actual size of the iso9660  filesys-
       tem.  One reason for this is that cd writers are allowed to add "run out" sectors at the end of an iso9660 image.

util-linux							     June 2011								ISOSIZE(8)