Business Insider

A guide to LED terminology for trade pros

Heather Mahr, a Ferguson author

by Heather Mahr


LED light bulbs are becoming increasingly popular for commercial and residential use alike. They provide superior energy savings and years of reliable performance, making them beneficial to trade professionals like commercial contractors, residential builders and facility managers. Because not all LED lamps are the same, the U.S. Department of Energy developed the LED Lighting Facts labeling program to clearly outline the energy use statistics for a particular bulb. Depending on its attributes, one LED bulb might be better suited for a specific application over another. Use this LED terminology guide to help you understand the information on an LED bulb label and be assured that you’re picking the right bulb for every project.

Average Rated Life

Bulbs are tested in batches to determine how long it takes for half of the bulbs to fail. This is known as the Average Rated Life, or ARL.


If 100 bulbs are powered and 50 of them fail after 1000 hours, then the ARL is 1000 hours. Some of the bulbs may have failed at different times throughout the test, but the average is 1000 hours because that’s when half of the batch failed.

Color temperature

A measurement that indicates the hue of a specific type of light source. Color temperature is measured by Kelvin, which is a temperature scale where one unit Kelvin is equal to one degree Celsius.on the Kelvin scale and ranges Colors range from cool, neutral to warm. The higher the color temperature, the cooler the hue of light.



2700K color temperature - LED bulbs of this color temperature will produce a warm white color similar to incandescent light, making it a suitable replacement for incandescent bulbs.

4100K color temperature - LED bulbs of this color temperature will emit a cool white light that is suitable for retail or work environments.

Get tips for choosing the right color and brightness of an LED light >>


The amount of light emitted by an LED lamp is measured in lumens. A bulb that shines brighter will have a higher number of lumens, whereas a bulb that emits less light will have a lower number of lumens.

Lumens per watts

The number of watts required to emit a certain number of lumens is a ratio known as lumens per watt (lm/W), or luminous efficacy. This term is particularly important for knowing the energy efficiency of an LED light bulb. If a bulb can emit a higher number of lumens while using a lower number of watts, it is considered to be more energy efficient than one that requires more watts to emit the same amount of lumens.

Example: A standard 60W incandescent bulb emits 800 lumens, whereas a standard LED bulb only requires 10W to emit 800 lumens. The LED bulb is more efficient than the incandescent bulb because it can emit a higher number of lumens while using significantly less power, or watts, than the incandescent bulb.


A watt is a unit of power. The amount of energy required for a bulb to emit light is measured in watts. The higher the number of watts required to power a lamp, the more energy used.

Now that you understand the language used to describe LED lighting, put your knowledge to the test and find the right LED lamp for your next project.

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Heather Mahr, a Ferguson author

Heather Mahr

As a writer, Heather is dedicated to providing readers with valuable information. She is passionate about helping people find the answers they need to make their life easier with her words.