IES Standard File Format

The majority of lighting fixture manufacturers are currently employing the Illuminating Engineering Society (IES) standard recommended file format for luminaire photometry (IES document LM-63-02).

The ASCII file format is shown below. This is exactly how any IES format file should appear when listed directly from a text editor. The standard for this format is included in the document LM-63-02, available from the Illuminating Engineering Society (

IES File Format

Each line marked with an asterisk must begin a new line. Descriptions enclosed by the brackets"<" and ">" refer to the actual data stored on that line.

All information is in standard ASCII format.


<keyword 1> <keyword data>

<keyword 2> <keyword data>


 <keyword n> <keyword data>

TILT=<filespec> or INCLUDE or NONE

<lamp to luminaire geometry>*

<# of tilt angles>*

<angles> *

<multiplying factors>*

<# lamps> <lumens/lamp> <multiplier> <# vertical angles> <# horizontal angles> <photometric type> <units type> <width> <length> <height>** 

<ballast factor> <future use> <input watts>

<vertical angles>

<horizontal angles>

<candela values for all vertical angles at first horizontal angle>

*<candela values for all vertical angles at second horizontal angle>


<candela values for all vertical angles at last horizontal angle>


* The four lines following the TILT line here are used if and only if TILT=INCLUDE.

** The terms width, length and height are measured in the Y, X and Z directions, respectively, and refer to the luminous dimensions.

NOTE: At the time of release of this publication, some luminaire manufacturers do not employ the IES LM-63-02 keyword scheme. Lighting Analysts programs do not require the LM-63-02 keywords; however, the AGi32 Instabase uses keywords if present. Without keywords, all information preceding the TILT= line is read as descriptive information.