Lumens & Lighting Facts
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:
- Energy saving incandescent bulbs use about 25% less energy than standard incandescents
- CFLs use up to 75% less energy than standard incandescents, and last about 10 times longer on average.
- LEDs use even less energy than CFLs, consuming only about 2% of the energy of a standard incandescent, and they will last up to 15 years without needing to be replaced.
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.
Lumens Measure Light Output
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 brigher; fewer lumens mean the light is dimmer.
Comparing Watts and Lumens
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:
- To replace a 100-watt incandescent bulb, look for a bulb that gives you about 1,600 lumens. If you want something dimmer, go for less lumens; if you prefer brighter light, look for more lumens.
- A 75-watt incandescent bulb gives you about 1,100 lumens
- A 60-watt incandescent bulb gives you about 800 lumens
- A 40-watt incandescent bulb gives you about 450 lumens
Learn more about lumens at www.energysavers.gov
The Lighting Facts Label
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).
Light Color Matters Too
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.
How A Light's Color is Measured
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.
- To use a CFL or LED that has the same color of light as your old incandescents, look for a bulb marked 2,700 - 3,000K.
- To use a CFL or LED with a more neutral color, look for one marked 3,500 - 4,000K.
- For more of a true daylight color, look for a bulb marked 5,000 - 6,500K.
You can read more about light color on the ENERGY STAR website.