November 4, 2026
Brightness Test: Know Your Lumens
How well do you know the testing behind the numbers on a lighting spec sheet?
The Inside Lighting Brightness Test is back for another round. Ten questions, four choices each, and a chance to find out how much you really know about the standards that shape our industry. A few questions should be easy. Others might make you reconsider something you thought you knew.
This month's quiz is presented in partnership with the Illuminating Engineering Society and focuses on ANSI/IES LM-79-24, Approved Method: Optical and Electrical Measurements of Solid-State Lighting Products.
LM-79 establishes standardized procedures for measuring the optical and electrical performance of LED luminaires and other solid-state lighting products. From lumens and efficacy to laboratory conditions and measurement methods, the standard helps ensure that the numbers on a photometric report have a consistent technical foundation.
But how much do you know about what happens before those numbers reach the spec sheet? This month's Brightness Test explores what LM-79 measures, what it doesn't, and some of the details that can influence the results.
Want to go deeper? Two good places to start:
10 Questions on LED Performance
