Wattage does not Determine the Brightness of a Lamp?

Some people say that the higher the wattage, the brighter the lamp. The idea seems right. Because wattage is one of the important factors affecting the brightness of lamps. We should know a premise, all other things being equal, the higher the wattage, the brighter the lamp.  

What’s more, it’s easy to confuse brightness with illuminance. Brightness is more about how the light is perceived by the human eye, while illuminance is the amount of light actually emitted by the lamp.


reflective of led light

Brightness & Illuminance

Illuminance is expressed in luminous flux (lx), and the unit is lm/㎡, which is lumens/square meter(1 lx = 1 lm/㎡). It can be understood as the amount of light per unit area that the human eye can see.


Luminous efficiency is also an important factor affecting brightness of lamps. The luminous efficiency reflects the relationship between wattage and luminous flux (lx). That is, how many lumens (lm) of lamp do you get per watt of light, lm/W.

Calculation formula: luminous flux = wattage * luminous efficiency

There are actually many factors that affect the brightness of lamps, such as the choice of light source, the material of the lampshade, and the duration of use. Therefore, it cannot be assumed that the higher the wattage, the brighter the lamp.

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