Need LDT instead?

IES was created by the IESNA (Illuminating Engineering Society of North America) and is widely used around the globe, but some european software only supports EULUMDAT (also known as LDT).
Both formats providing almost the same informations, only big difference; the IES does not contain any informations about the correlated colour temperature (CCT) and the colour rendering index (CRI).

If your software only supports LDT, there's a free way to convert our IES to LDT. Here we will explain, how to do this...

First you have to download the free IESviewer from
Make sure you select the latest version!

After you unziped the sofware, you can execute the program.
Navigate to the downloaded IES-file and context-click on the IES-file you like to convert.
Chose "Export to LDT"