Watts vs Lumens

Ever since energy efficient lighting has been on the rise, the word lumens has been trending. Most lighting manufacturers now prefer measuring the strength of a bulb by lumens rather than watts.


First of all, let’s define some terms.

Watts = a measure of how much energy is being used.
Lumens = a measure of how much brightness is being produced.

When shopping for a light bulb you would want to look for the bulb that uses the least watts, so as to cut that electric bill, and produces the most lumens, for optimal brightness.

So how do you go about finding all that information? When you go out to buy a light bulb you want it to be a quick and easy process, not a scavenger hunt.

Easy! You find information about your lightbulb the same way you find information about your food – on the nutrition facts label. Or rather, the lighting facts label.

Take a look:

The bulb above has a brightness of 820 lumens and uses 60 watts of energy. Some quick math tells us that this bulb’s output, for every watt, is around 14 lumens. That number is referred to as the ​ luminous efficacy ​- how much lumens are produced for every watt.

A luminous efficacy of 14 is not very efficient at all. This bulb is an incandescent. Realize that this bulb will only live for 1.4 years, and will cost $7.49 each year. That’s quite a lot for one bulb; if you have only 10 bulbs at home, this will add up to about $75 per year! Let’s compare that to an LED bulb:

This bulb has a brightness of 800 lumens and uses only 9.5 watts. The resulting luminous efficacy is around 84. This is one efficient bulb indeed! In addition, this bulb will live for a staggering 22.8 years and will only cost $1.14 a year! This is clearly a smart purchase.

For more information on light bulb guides and everything lighting, feel free to contact one of We Green Energy’s friendly representatives!

Sarah Landau