Dimmable Light Bulbs Down Lights & Recessed Flood Lights Grow Lights Spot Lights LED Strip Lights LED Tube Lights RGB Color Lights & Strips White LEDs Replace up to 35W Replace up to 40W Replace up to 60W Replace up to 75W Replace up to 100W LED Kitchen Lighting PAR Light Bulbs Specialty Lighting 12 Volt E12 & E14 Base E27 & E26 Base G4 Bulbs GU10 Bulbs MR16 Track Lighting Commercial Lighting Industrial Lighting Aquarium Lighting Home Lighting Interior Lighting LED Mood Lighting Office Lighting Marine Lights
LED Lighting University - LED Light Bulb Brightness and Illumination by EagleLight
EagleLight's LED University: Light Bulb Brightness Explained
Various Definitions of LED Brightness: lux, lumen and wattIn this lesson we are going to define some of the many terms used in light brightness such as watt, lumen, and lux.
Here we will discuss:
This discussion is not a rigorous scientific analysis, it is intended to offer an understanding of a few of the various terms used related to LED light bulb brightness.
Watt as a measure of LED brightnessA measure of brightness used in the past was the wattage of a light. With more efficient lighting products like CFL and LEDs, use of the watt is no longer an accurate means of determining brightness across multiple lamp technologies. For example: a 75 Watt incandescent bulb, 18 watt CFL and a 9 watt LED may all produce the same amount of usable light. Obviously watt is not longer a viable means to measure the brightness of a light source.
LED Lumen as a measure of brightnessThe LED lumen measures the total amount of visible light from a light source. Unfortunately some light may be used to light areas not even visible to the viewer. Such as the lighting of the inside of a fixture. This is why the measure of the light found on the projected surface is often a much better measure of applicable light. LED lumens often times are less than the lumen measure of an other light technology for the same amount of brightness on the working surface. This is due to the directed nature of LED packaging. This direction of the LED lumen results in greater use of the available light.
LED Lux as a measure of brightnessThe measure of the amount of visible light on a surface, like the lux, is a good way to determine the amount of "usable" light created by a light source.
The radiant flux is the total amount of light generated, this includes light that is not visible to the naked eye like infrared and ultraviolet.
The luminous flux is an adjustment to the measurement of radiant flux that measures only that light perceived by the human eye. The LED lumen (Lm) is a measure of the amount of LED light produced that we can potentially see.
The luminous intensity is an adjustment to the luminous flux that measures the amount of light on a surface. Think of this as the usable light.
When purchasing LED light bulbs you may see that the lumen listed on the LED does not match that of an incandescent, but the lamps offer the same about of light on your desk or table. This is because the light from LEDs are often "directed light" where an incandescent light shines light in all directions: only a part of which is used to light up what you are intending.
When purchasing light bulbs the lumen is one measure to determine relative brightness, however use of the lux gives you a measure of the light hitting the surfaces you are trying to light.
When choosing a lightbulb, determine the appropriate lux or lumen required and then select that bulb with the fewest watts. Lower wattage means lower electricity bills. Checking LED lumens directly against traditional bulb lumens is only appropriate under certain lighting conditions and certain light bulb shapes and fixture designs.
For more technical information, physics and some math on the topics in this lesson you can refer to the Wikipedia definitions.