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The Facts About Incandescent Light Bulbs

I still like to buy incandescent bulbs sometimes, and this is why.

How Incandescent Light Bulbs Changed Over Time

Rumors of the incandescent light bulb's demise have been greatly exaggerated. The screw-based light bulbs that many consumers know and prefer as their favorite method of lighting their homes are still widely available, though they have now become more energy-efficient and now boast a black and white "lighting facts" label.

In the United States, the Energy Independence and Security Act of 2007 kicked off a huge shift in how light bulbs are manufactured, focusing in great part on making incandescent bulbs more efficient. Old incandescent bulbs lose about 90 percent of their electricity in the form of heat, which is why they get so hot to the touch. Under the new standards, these bulbs use fewer watts (energy) to produce the same amount of light (lumens).

Lumens and Watts

When shopping for new incandescent bulbs, the most important thing to look at is actually the number of lumens, not the wattage. Watts refers to how much energy the bulb uses while lumens are a measure of the bulb's light output.

While it remains important to make sure that you do not buy a bulb that uses more wattage than the fixture will accept (many fixtures have limits of 100 or 150 watts) so as to prevent the risk of an electrical fire, finding the best brightness and light quality for your needs and preferences is a matter of looking at the lumens.

For the sake of familiarity in explanation, the old and less-efficient watt numbers will be used in the table below.

Comparing Watts to Lumens










Fewer Watts, Same Output

The phase-out of less-efficient wattage in American incandescent light bulbs began in January 2012, when the staple 100-watt bulb shed a few inefficient watts to become a more efficient bulb that emits about 1600 lumens while using about 72 watts. A year later, the 75-watt bulb also changed, providing 1100 lumens for about 53 watts. In January 2014, the changeover will be complete when 60-watt bulbs shift to about 43 watts and 40-watt bulbs use about 29 watts.

Light Appearance: Warm vs. Cold Light

Do you like a warm, yellowish glow on your light—which is associated with traditional incandescent bulbs? Or maybe you'd rather have a brighter white glow that more closely mimics the clarity of a bright, sunny day? There's an ideal use for each of these different light temperatures and an easy way to find out what kind of light is produced by incandescent bulbs.

Look to the sliding scale at the bottom of the black and white Lighting Facts table, which has been standard on bulb boxes since 2012. You will see a little arrow and then a number such as "2700K" printed below it. That K stands for Kelvin, the temperature scale on which a bulb's color temperature is measured.

Kelvins and Quality of Light

As a general rule of thumb: the higher the degrees Kelvin you see, the 'cooler' and closer to daylight the light will be.

Light Temperatures

Temperatures (Kelvin)Types of light


Warm, soft white


Neutral, cool white


Natural, daylight

Change What You Look for

The incandescent light bulb as we know it has not been banned or removed from the market. You will still be able to buy incandescent bulbs if you prefer them over fluorescent or LED bulbs. What has changed, though, is the efficiency of the bulb. The most important measure of a bulb's light output, the lumen, has been brought front and center along with the color temperature scale.

There's also another benefit to the increased efficiency of incandescent bulbs and it might just be the most important of all: saving money on energy!

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.


IM SAD DONT TALK TO ME on July 22, 2020:

i need this for school lol

:( on November 25, 2019:

This was too paragraphy

joe mumma on October 16, 2019:


sparecoochymam on April 15, 2019:

I was frankly offended by the lack of directness here in these facts, these facts were factual, but the thing is that they were not represented in a direct way and despite how factual this articale may in fact be, it was not direct, and that is my issue with this article, how indirect it was.

Penlopoopy on February 11, 2019:


4 years ago

That was really informative!! Thanks!

HA! the only one.

Yaboiii123 on November 07, 2018:

These were not facts they were long paragraphs I wanted quick and easy facts this was terrible

jardyn on October 24, 2017:

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juan on March 23, 2017:

thank you good sir!

Noneofyourbusiness on December 05, 2015:

I found this not useful it was all right but not the best.

Nottelling!!! on January 22, 2015:

That was really informative!! Thanks!