How Bright Are LED lights? The Facts About Lumens

August 18, 2016

Are you are considering LEDs, but afraid they won’t match or look as bright as your incandescent lights? Well, let’s talk about lumens, and how LED lights can look just as bright while using a tenth of the energy of incandescent lights.

The actual lumen output of a C7 or C9 incandescent bulb is about 24 lumens. The illumination comes from the filament in the center of the bulb, and is evenly distributed as it shines through the clear bulb. In this photo, the incandescent bulb is all the way on the left.

LED lights on the other hand, are directional, that means their lumen output doesn’t spread out the way a filament’s light output does. It goes in one direction. So, a direct comparison of the light output can be tricky and misleading.

In order to create a fully glowing look in a Christmas light, an LED light needs to be housed in a faceted bulb that breaks up the light in all directions. The third and fourth lights pictured are warm and cool white LEDs, respectively. The faceting makes the light fill the whole bulb. But the brightness varies depending on what angle of facet you see the light through—which creates a wonderful twinkle.

A non-faceted bulb can break up the light a little bit, but as you can see on the second bulb from the left (“champagne smooth”), it is very bright but does not “fill” the bulb. It appears bright at a distance, but as you can see the light has a slightly different quality from an old-fashioned incandescent bulb.

The actual lumen output of an LED light depends on the color. Just as a colored bulb will dim a white incandescent light, colored LED bulb housings and colored LED lights will have a lower luminosity than white ones. White LEDs are brightest, the warm and cool C7 and C9 bulbs averaging around 4 lm. The colored lights get dimmest at either end of the spectrum, blues and reds coming in dim at around half a lumen. (But remember, the same principle applies to a colored incandescent bulb! A red painted bulb housing will lower the luminosity of even the brightest incandescent filament.) Here are all the numerical details.

Model # of LEDs Color Power Draw (Watts) Total Output Power (mW) Light (lm)
C7 Faceted 3 RED 0.96 1.3 0.4
ORANGE 1.6 0.7
YELLOW 1.5 0.5
BLUE 3.9 0.4
GREEN 2.7 1.8
PURPLE 3.4 1.2
COOL WHITE 6.3 3.2
WARM WHITE 6.5 3.9
C9 Faceted 5 RED 0.96 2.6 0.7
ORANGE 2.8 1.2
YELLOW 1.2 0.7
BLUE 11.6 0.9
GREEN 5.8 3.7
PURPLE 5.4 1.8
WARM WHITE 7.8 4.7

So how is it that at a fraction of the lumen output, an LED light can look just as bright as an incandescent bulb? The answer is in the directing and breaking up of the light. By refracting a very focused LED light in many directions, or even down the length of a smooth bulb, the eye will perceive nearly as much luminosity from an LED as from a filament lit up with ten times the energy pouring out of it. (See below picture unlit to show faceted and smooth bulbs.)

The quality of light is slightly different between LEDs and incandescents, but the purity of the colors, the low energy cost, and the ability to string four times as many LEDs onto a single strand of lights (due to the low energy draw), means going with LEDs will save you time and money down the road. In fact, a quantity of 100 incandescent 7W bulbs draws about 6 amps of power. The same quantity of LEDs? Less than 1 amp! LEDs save energy and money, and more importantly will add plenty of brightness and sparkle to your holiday decorating.

Fully stocked with incandescents but wanting to make the switch to LEDs? Update to energy-efficient lighting with our retrofit LED bulbs!