Article | Watts or Lumens? How to Choose the Right LED Bulb Replacement

The old days of selecting light bulbs by watts are over. We are now faced with lumens instead of watts. Let's learn how to select the right LED bulbs by using lumens. It's not so hard.

Step 1. Understand Watts: Watts are a measure of energy consumption. When we pay our electric bill, we pay for the number of watts we use. A 60-watt bulb consumes 60 watts of energy. Since we've used 60-watt bulbs for so many years, we associate a certain level of brightness with 60 watts. We can't do that anymore since we have new light sources that give us more light with fewer watts. Instead, we need a measurement for visible light energy - lumens.

Step 2. Understand Lumens: A lumen is a measure of visible light energy. More lumens equals a brighter light. All lighting manufacturers are starting to tell us how many lumens are produced for each of their lighting products. We see these lumen numbers on the new Lighting Facts labels found on all new LED bulb packages. It will take awhile for us to get used to using lumens instead of watts, but if we want to make the best lighting choices, we need to search for and compare these lumens.

Step 3. Understand Efficacy (Lumens/Watt). Now that we understand watts and lumens, we can use both terms to come up with efficacy or lumens/watt. Sometimes the term "luminous efficacy" is used. This is a measure of how well a light source converts energy (watts) into light (lumens). The old technology of tungsten incandescent bulbs only had an efficacy of about 15 lumens/watt; LED technology can produce about 60 lumens per watt. In other words, LEDs are about 4 times more efficient at producing light than incandescent bulbs. This 4-1 ratio is a rough guide of how to calculate what LED bulb to use when replacing an incandescent bulb.

For example, if you need to replace a 60 watt incandescent bulb with an LED bulb, then divide 60 watts by 4 to get 15 watts - that will be a good guess. But we should note that efficacy varies wildly from manufacturer to manufacturer so you should check the Lighting Facts label and try to match lumens. Also, a label will sometimes tell you that an LED bulb has an equivalent brightness, but sometimes it doesn't. Refer to the charts at the end of this article for a ready reference. Also, note that all VOLT® Indoor & Low Voltage Landscape LED bulbs have the incandescent or halogen equivalent wattage displayed on each of their product pages. We make the switch-over to easy.

Lumens and watts conversion charts for your reference1:

Lumens for Light Source Watts
Lumens Incandescent Watts LED Watts
375 25 6
450 40 10
800 60 15
1100 75 19
1600 100 25
2600 150 38
3000 200 50
Luminous Efficacy
Light Source Luminous Efficacy
Incandescent 12-18
Halogen 16-24
LED 30-90

1Data from Federal Trade Commission.

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