What is an IES File?

How to Open, Edit, & Convert IES Files

Picture of the IES file icon

A file with the IES file extension is an IES Photometric file that stands for Illuminating Engineering Society.

IES files contain data on light for architectural programs that can simulate light. They hold information about how light will appear, like on roads or in buildings.

Note: ISE files share the same letters as the .IES file extension. However, ISE files are either InstallShield Express Project files or Xilinx ISE Project files - they open with InstallShield and ISE Design Suite, respectively.

How To Open an IES File

IES files can be opened with Lighting Analysts' Photometric Toolbox, Autodesk's Architecture and Revit software, RenderZone from AutoDesSys, AcuityBrands' Visual lighting software, Philips Gardco Lighting's Footprints, and LTI Optics Photopia.

Note: If you need helping using your IES file in Revit, see Autodesk's tutorial on how to specify an IES file for a light source.

An IES file can also be opened for free with IESviewer, as well as online through AcuityBrands' Visual Photometric Tool.

A simple text editor like Notepad++ can also open IES files because the files are in plain text. Doing this won't let you see any visual representation of the data though, just the text content.

If you find that an application on your PC does try to open the IES file but it's the wrong application or if you would rather have another installed program open IES files, see my How To Change the Default Program for a Specific File Extension guide for making that change in Windows.

How To Convert an IES File

An IES file can be converted to an EULUMDAT file (.LDT) using this online converter. You can also do the opposite and convert LDT to IES. Eulumdat Tools should be able to do the same thing but it works from your desktop instead of through your web browser.

PhotoView isn't free but can convert IES files to formats like LDT, CIE, and LTL.

Though it likely won't be of any use, you can convert an IES file to another text-based format using the Notepad++ program I mentioned above.

The DIALux program can open ULD files, which are Unified Luminaire Data files - a similar format to IES. You might be able to import an IES file into that program and then save it as a ULD file.

More Help With IES Files

See Get More Help for information about contacting me on social networks or via email, posting on tech support forums, and more. Let me know what kinds of problems you're having with opening or using the IES file and I'll see what I can do to help.