What Is an ISZ File?

This article describes what an ISZ file is, how to open one, and how to convert one into a more common format like ISO, RAR, ZIP, etc.

What Is an ISZ File?

A file with the ISZ file extension is a zipped ISO disk image file. They are compressed, and sometimes encrypted, ISO images created by EZB Systems for the purpose of saving disk space.

It can be split into smaller parts so that the data can be saved on multiple storage devices but still be joined together as a whole file. Usually, the first file in the sequence is saved with the .ISZ file extension, but the second uses .i01, the third .i02, and so on.

How to Open an ISZ File

EZB Systems (the developers of the ISZ format) offers the program UltraISO for not only creating ISZ files, but also opening them. To do this (even with the trial version), go to Tools > Uncompress ISZ. This process converts the ISZ file to an ISO file and put the ISO in the same folder as the ISZ file.

Alcohol 120% can open ISZ files, too, but it's also not a free program.

DAEMON Tools Lite and WinMount Free Edition mount ISZ files, which opens the file as if it's a storage device so you can browse the contents.

For example, a quick way to open the file with DEAMON Tools Lite is to first open the program and then use the Quick Mount option to browse for and select the ISZ file—the app will find a suitable letter to use and then mount the ISZ file as a virtual drive, meaning the computer will think the data is on a disc.

You can then browse through the file as you would browse through the contents of a disc, which, of course, is much like clicking through files and folders stored on a flash drive or your computer's hard drive.

How to Convert an ISZ File

One easy way to convert ISZ to ISO is to use the UltraISO program I mentioned above. It's very simple to do, and it works even with the trial version of the program.

UltraISO also lets you convert it to other image file formats like BIN, NRG, MDF, and IMG, through Tools > Convert.

AnyToISO is another way to save an ISZ file to the much more common ISO file format.

If you want to convert the files inside the archive (and not the ISZ file itself), then you should first convert the ISZ to ISO using either method just mentioned, and then use a free zip/unzip program (like 7-Zip or PeaZip) to extract the contents out of the ISO. The files that remain can probably be converted using a free file converter.

Converting one to an archive format like RAR, ZIP, 7Z, etc., is best done if you first convert the ISZ to ISO. Then you can use a tool like CloudConvert to convert the ISO to an archive file. Another option is to use a file decompression program like 7-Zip to extract the files out of the ISO and then use the same program to compress the files to 7Z, ZIP, etc.

Still Can't Open It?

The first thing you should check is that the file extension truly reads ".ISZ" and not something similar like .SZ, which is the file extension Winamp uses for program skins. The file extensions are similar, but they have nothing to do with each other.

Another one to watch for is ISS. Although it's just one letter off, those could be audio files or text files, depending on the format. But both are very different from the archive format described on this page.