Light Bulbs: Watts, Lumens, and Kelvin
typhoonlighting.comUntil recently there was little need to really know your way around a lightbulb aisle. Most people know what lightbulbs they need for their fixtures and have a general idea about the wattage required for their lamps and ceiling lights. Maybe they’ve figured out halogen bulbs for certain fixtures or by chance found themselves with xenon bulbs in a light or two.
Now it is high time to get our lighting terminology down, so we can figure out LED lightbulbs! LED technology has advanced rapidly in the past few years, making LED bulbs more prevalent and affordable. Now many of us find ourselves in the market for these new bulbs, but also find ourselves scratching our heads as we try to figure out which ones to buy. With a few new vocabulary words and some better understanding of light bulbs, we’ll be well on our way to saving money and energy while sitting in the glow of the perfect energy efficient light.
Watts vs Lumens
Forget what you used to think about wattage and start thinking in lumens. In the many decades that incandescent light bulbs reigned, we all came to equate watts with how much light a bulb provides. Wattage is in fact, how much energy a light bulb uses. And in this day and age, we are finding ourselves needing to use less and less energy (watts!) to provide the same light, which is great for our pocket books as well as the environment. We just need to understand lumens.
Here is a simple chart to help you understand lumens:
|Lumens||Incandescent Wattage||LED Wattage|
|450 lumens||40 W||5 W|
|800 lumens||60 W||10 W|
|1100 lumens||75 W||15 W|
|1600 lumens||100 W||19 W|
K is for Kelvin
As we learn to navigate the new light bulb landscape, we need to get familiar with our friend Kelvin. Kelvin is the scale used to measure the color output of the light. The Kelvin scale for light bulbs used in residential lighting usually goes from 2700K to 6500K, with 2700K being the warmest more yellow light and 6500K being a colder and almost blue light.
Warning! Don’t be misled by “daylight bulbs.” Often the bulbs in the 4500K to 6000K range are marketed as daylight bulbs. You may very well like the color output of these bulbs, but they do not necessarily mimic daylight. What they are intended to mimic is the direct sunlight of full sun at midday.
A quick guide:
Warm White Light (giving a more yellow glow) – up to 3000K
Cool White Light – 3100K – 4500K
Bright White or “Daylight” – 4500K – 6500K
Lighting Facts Box
So when you’re scratching your head in the light bulb aisle, pick up a lightbulb box and find the lighting facts box. Just like you may flip to the nutritional information box on a food product, this box will give you all the information you need.
Line 1: Brightness (given in lumens)
Line 2: Estimated yearly energy cost (based on an average daily usage described on the package)
Line 3: Estimated life of the bulb (based on the same average daily usage)
Line 4: Light Appearance (based on the Kelvin scale)
Line 5: Energy used (using wattage as the measurement)
Line 6: Contains Mercury (for Compact Fluorescent CFL bulbs)
For more information check out this link: