05 Mar, 2020 Nancy Tart

Lumens Versus Lux

When navigating the world of Lighting, one will find lamps with Lumens and Lux ratings.  Why are there two separate ratings and what do they mean?

Lumens is the measurement of luminosity at the source.  This means that if two lamps are rated at 860 Lumens, they release 860 Lumens from the bulb.  This measurement is helpful in comparing lamps for your fixtures. 

Lux is considered more important when comparing similar lamps as it measures Lumens per square meter.  Lux is a measurement of the extended output of the lamp.  It measures how much area the lamp with light.

For example: one incandescent lamp rates 1000 Lumens and the LED lamp designed to replace it rates 600 Lumens.  However, the incandescent is 233 Lux while the LED is 368 Lux.  There is more area lit by the LED lamp despite it exerting lower Lumens at the source.

Think of it this way: Would you rather see more space illuminated or a brilliant spot?  In most household applications it is the space we want illuminated, not the fixture.  Therefore, when comparing lamps, the greater Lux is what we want to see more than the greater Lumens.