Lumens to lux

Transforms the luminous flux into lumens (lm) to lux (lx) thanks to our online light calculator. To do this, you must know the amount of light in lumens, the area of the area in square meters or, failing that, the spherical radius of the light source.

How much is a lux?

A lux is a unit of luminous flux equivalent to one lumen per square meter and is often used for measure the amount of light in a room or room.

To calculate the amount of lux we must know the number of square meters of the room or the spherical radius of the light source. With these data we will be able to convert lumens to lux as we are going to see in the next point.

How to switch from lumens to lux

Lumens to lux converter

To convert from lumens to lux in square meters we have to use the following mathematical formula:

Ev(lx) = ΦV(lm) / A(m2)


  • Evilluminance or luminous flux in lux (lx)
  • ΦV(lm)is the flux in lumens of the light source in the room.
  •  A(m2)is the area in square meters of the room.

In case you do not know the area of the room, you can convert from lumens to lux using this other mathematical formula in which we use the spherical radius of the light source:

Ev(lx) = ΦV(lm) / (4⋅π⋅2(m))

In the above formula we can see that the illuminance in lux (lx) is equal to the luminous flux in lumens divided by four times PI times the spherical radius in meters squared.

Practical example of lux

Let's imagine that we have a 50W spotlight emitting 500 lumen. The light sensation of this spotlight will depend to a great extent on its opening angle and the space to be illuminated.

If with that bulb we have to illuminate a room of 5 square meters, we will have 100 lux in total, which is a very low figure for a space of this size. However, if we use that bulb to illuminate a room of 1 square meter, then we will have 500 lux, which is already quite a lot of light.

1 thought on “Lúmenes a lux”

  1. I have a case a signaling lamp gives me 200 lumens and with an angle of 120 degrees at three meters high I would like to know how many lux it gives me or if I want to reach 50 lux.
    Thank you for your cooperation and understanding


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