What Is an SZN File?

An SZN file stores 2D or 3D drawings for the HiCAD computer-aided design software

By
Tim Fisher
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Tim Fisher
Senior Vice President & Group General Manager, Tech & Sustainability
  • Emporia State University

Tim Fisher has more than 30 years' of professional technology experience. He's been writing about tech for more than two decades and serves as the SVP and General Manager of Lifewire.

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Updated on April 11, 2023

What to Know

  • An SZN file is a HiCAD 3D CAD file.
  • Open one with HiCAD or HiCAD Viewer from ISD Group.
  • Convert to a different format with those same programs.

This article explains what an SZN file is used for and how to open one or convert one to a different format.

What Is an SZN File?

A file with the SZN file extension is used by the HiCAD computer-aided design software to store 2D or 3D drawings.

SZN Files

How to Open an SZN File

SZN files can be opened with ISD Group's HiCAD. The program isn't free to use, but there is a demo you can download that should also provide the same support for these files.

This is no longer the format used by new versions of the program, which default to using SZA and SZX files.

The same company has the free HiCAD Viewer that can open SZN files, too, but only if they contain shaded 3D models. This means 2D models or glass models that are saved in the SZN format can't be opened with the viewer. However, it can work with some other file types used with HiCAD, like 2D drawings in the ZTL format, plus SZA, SZX, and RPA files, as well as HiCAD Parts and Assemblies files in the KRP, KRA, and FIG format.

On the HiCAD Viewer download page are several versions of the program. The latest release only works with 64-bit versions of Windows, while older editions are offered in both 32-bit and 64-bit versions. Your choice depends on the type of computer you have. See How to Tell If You Have Windows 64-Bit or 32-Bit for help.

If you suspect your file has nothing at all to do with HiCAD or CAD drawings in general, try opening it with a free text editor. If the file is full of just text, then your SZN file is just a text file that can be used normally with any text editor. If most of the text is illegible, see if you can pick out something identifiable from the mess that can help you research the program that created your file; it's usually also the same program that can open it.

How to Convert an SZN File

HiCAD Viewer can save open files to a different format. It's likely that you can use that program to convert the SZN file to some other similar CAD-related format.

The same goes for the full HiCAD software. There's most likely an option for conversions in the File or Export menu.

Most common file formats can be converted using a free file converter, but if you follow through with this link, you'll find that none of the online services or converter programs support this particular format.

Still Can't Open It?

If your file doesn't open as described above, there's a good possibility you're just misreading the file extension and confusing a different file for one with the SZN file extension.

For example, this extension is very similar to SZ used by the Winamp music playing software as a custom interface, or "skin." The two formats have nothing to do with each other, even though it's easy to mix up their file extensions.

Here are some other examples:

  • ISZ: Zipped ISO disk image
  • SZS: Video game data file
  • SZ4: E-triloquist Phrase Library Format file

If you discover that your file is in none of these formats, research the real file extension to see which programs can be used to open or convert it.

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