Whats a lumen and whats a watt? What?!

another great article from Ledified;

One of the most common questions that consumers have about LED lighting is how lumens compare to the wattage rating, watts being something that we are all so used to seeing on incandescent bulb packaging. The reason this is such a confusing concept is because lumens and watts measure different things. Lumens measure the total amount of light emitted by the bulb while watts measure the amount of power consumed by the bulb. Watts do not tell you how bright the bulb is, lumens do.


Estimating Light Output

It is easy to estimate how bright an incandescent bulb is; the higher the wattage rating, the more light emitted. We all know that a 100W bulb is far brighter than a 40W bulb. Today there are so many different types of light bulbs to choose from that it’s hard to use wattage ratings to figure out how bright a light bulb will be. LEDs, halogens, and CFLs are all more efficient than incandescents, but those efficiencies differ from bulb type to bulb type. You can’t easily compare a 60W incandescent with a 9W LED with a 12W halogen and know which one will be brighter. All you know is that the 60W will use the most power.

To help consumers better compare light across the different types of bulbs, light bulb manufacturers are including a lumens (lms) number on the packaging. Lumens measure the amount of light emitted by a bulb, regardless of the type of bulb or how much wattage it uses. Lumens are a more accurate indicator of light because it tells you how the bulb performs, as opposed to how much energy it consumes (watts). The higher the lumens, the more light the bulb emits, but a high lumen value does not necessarily equate to a high wattage need.


Comparing Lumens And Watts

To compare LED bulbs with other types of light bulbs look at the packaging. You’ll see the number of lumens produced as well as the wattage of the bulb. Compare the lumen numbers to see if the lightbulbs will give off a similar amount of light, then look at the wattage requirements to see how much energy each bulb will use. Using these two numbers you can easily identify how bright a light will be and how much energy it will consume. To choose the most energy efficient bulb for your needs, find ones that have the light output that you need, then choose the one that has the lowest wattage.


Gauging The Brightness Of LED Lights

Until you’re more comfortable using lumens to gauge how much light a bulb will produce, use these approximations:

  • 40W = 450 lumens
  • 60W = 800 lumens
  • 75W = 1100 lumens
  • 100W = 1600 lumens
  • 150W = 2600 lumens

Using the approximations above, if you want to replace 60W bulbs with LED bulbs that emit comparable light, you’ll need to choose those that have 800 lumens.

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