What is a lumen (LM)? A lumen is a measurement of visible light emitted from a light source as it appears to the eye.
Brightness=Lumens
Understanding Luminosity?
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Luminosity is the amount of light emitted by a light source radiating out in all directions.
Unfortunately not all of this light is useful, with florescent lighting the light source is emitted equally in all directions, 360° degree.
Much of this light may not be useful but it is still counted in the total lumen rating. In comparison an LED tube light has a beam angle of 120 degrees. All of the light generated by the LED tube light is focused downward in the 120 degree area.
bottom line:
Two light sources with identical luminous output and the LED light source is much brighter to the eye.
Watts have always been synonymous with brightness, after all everybody knows a 100 watt bulb is brighter than a 60 watt bulb.
However, wattage isn't an indication of brightness, wattage simply represents the amount of energy needed to use the bulb.
With the advent of so many types of energy-efficient lighting products, each with different efficiently ratings we needed a standard of measurement we could use with all mediums.
Warning
Manufactures lie! Do not assume the box is correct about the luminous output. I have compared products from Amazon, Ebay, and even the big box stores.
Identical products, with identical components claiming outrageous luminous output.
Worse yet is the rampant use of under powered LED drivers.
The LED industry is an extremely competitive industry. Manufactures will do almost anything to cut corners.
Consumers are always shopping for the best price.
When two products look identical in appearance it's natural to assume the components inside are the same.
