When buying light bulbs, you used to just have one choice - incandescent bulbs. You picked the size you wanted based on watts.
Today, there are a lot more options:
Not only are there lots of choices, but the way you pick a light bulb is changing, too. Now, instead of buying based on watts, you should look for lumens.
Most people know that a 100-watt light bulb is brighter than a 40-watt light bulb. But did you know that a watt is actually a measure of how much energy the bulb consumes, not a measure of how much light it puts out?
That's where lumens come in.
Lumens measure the amount of light produced by a bulb. More lumens mean the light is brighter; fewer lumens mean the light is dimmer.
Because not all 100-watt incandescent light bulbs produce the same amount of light (lumens), you can't use a simple formula to convert watts to lumens. But here's a good rule of thumb you can start with:
Learn more about lumens at www.energysavers.gov
Look for the new Lighting Facts Label to make sure you buy bulbs that are right for you.
Like the helpful nutrition label on food products, the Lighting Facts label helps you learn more about what you are purchasing. The label provides the lumens—or brightness—of the bulb, the estimated operating cost for the year, and the color of the light (from warm/yellowish, to white, to cool/blue).
Most of us grew up with the soft yellowish glow of incandescent lights, which is often called "warm white" or "soft white" on light bulb packaging. Today, you can buy all kinds of bulbs in a wide variety of colors, from warm to cool.
A light's color is measured on the Kelvin scale. Lower Kelvin numbers mean the light will be warmer. Higher Kelvin numbers mean the light will be cooler.
You can read more about light color on the ENERGY STAR website.
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