Design Nomenclature / Light & Optics

IES profile

Also called IES file, photometric web, LM-63, photometric data

Measured photometric data for a real fixture, tabulating luminous intensity in candela across a grid of angles. A renderer reads it to reproduce that luminaire's actual beam — the scallops, the cut-offs, the side lobes — instead of an idealized cone. It carries distribution and total flux, not spectrum.

Two-column comparison: a spot light described as an idealized cone defined by a cone angle and a smoothing parameter, set against an IES profile described as measured candela values per angle carrying a real fixture's scallops, cut-offs and side lobes.

In practice

Manufacturers publish them free. Using the real fixture's file is the cheapest realism available in architectural rendering, and nobody does it.

Not to be confused with

How this term connects

CandelaIlluminanceKelvinLumenSpot lightIES profile
Related Confused with