Tech Tips

Lumen vs Lux: What are the Differences?

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.