isosize - Man Page

output the length of an iso9660 filesystem

Examples (TL;DR)


isosize [options] iso9660_image_file


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


-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 filesystem. One reason for this is that cd writers are allowed to add "run out" sectors at the end of an iso9660 image.

-h,  --help

Display help text and exit.

-V,  --version

Print version and exit.

Exit Status




generic failure, such as invalid usage


all failed


some failed

Reporting Bugs

For bug reports, use the issue tracker at


The isosize command is part of the util-linux package which can be downloaded from Linux Kernel Archive.


2023-10-23 util-linux 2.40-rc1 System Administration