In the Spotlight #1: Candlepower Versus LumensWhen looking at the specifications of light bulbs it is very easy to get overwhelmed. There seem to be an extraordinary number of units of measurement for something that seems pretty straight forward, light. One of the two most commonly confused and confounding measurements are candlepower and lumens. We have received numerous customer calls and emails requesting an explanation of how these two units differ, so that will be the focus of this article. Of the two measurements, candlepower is more obscure and I think less fully understood. Candlepower refers to the lighting concentration of a unidirectional light source. In other words, candlepower measures the intensity of light in a single direction. Candlepower, often measured in candelas, are therefore a popular unit of measure for flashlights and focusable light sources like ellipsoidals or spotlights that can project a single narrow beam. A related unit of measurement is center beam candlepower (CBCP) which is a measurement of the intensity of light at the center of a bulb’s light beam.
With the definition of candlepower in mind, let’s move on to lumens. Lumens (lm) are unit of measurement for the measure of total illumination of a given light source. The lumens rating is one of the first specs people look at when comparing bulbs because it does give a fair indication of how bright their light source will be. In particular, measuring the lumens a light source puts out is helpful for lamps produce a diffuse light, like a flood. Measuring lumens is not as useful for highly directional bulbs, like a spot, because you will likely be more concerned with the unidirectional brightness of a bulb rather than its general brightness.
Hopefully the distinction between candlepower and lumens has been made clear in this article and now you can wade through the sea of technical specifications that awaits you. If not, then feel free to post a message or call BulbAmerica toll free at 1-877-622-0897 with any remaining questions you have.