Lumen is widely seen in projector specifications. But some projector suppliers also use Lux to label brightness. What are the differences between Lumen and Lux?

Lumen is a unit used to describe the luminous flux, which refers to the luminance of the projector. luminous flux measures the total quantity of visible light emitted by a source per unit of time. Also known as the light energy absorbed by an illuminated object per unit of time.

Lux is a unit of illuminance, which measures how much the luminous flux is spread over a given area.

That’s to say, lumen measures the total quantity of visible light, while illuminance describes the intensity of illumination on a surface.

You can convert lux and lumen as follows:

1 Lux= 1 lumen/m2

Lumen=Lux*screen area

For example, the projector has fixed 2,000 lumens, the screen area is 1m2, then the lux is 2,000 Lux; if the screen area is 10 m2, then the Lux is just 200.

For the same projector, the larger the screen area, the smaller Lux it has; the smaller the screen area, the bigger the Lux. In addition, the closer to the light source, the bigger the Lux value.

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