Lumens to lux calculator
Convert luminous flux from lumens (lm) to illuminance in lux (lx) easily. Perfect for lighting design, photometry, and light measurement calculations. Obtain accurate lux measurements by converting lumens using this convenient online tool.
what is Lumens to lux calculator
Converting lumens (lm) to lux (lx) requires knowledge of the distance between the light source and the surface being illuminated. Lux is a unit of measurement for illuminance, which indicates the amount of light falling on a surface.
To calculate lux from lumens, you can use the following formula:
Lux = Lumens / (Area in square meters)
To use this formula, you need to know the total lumens emitted by the light source and the area over which the light is distributed.
For example, let's say you have a light source that emits 1000 lumens, and you want to find out the illuminance in lux at a distance of 2 meters from the source. If the area being illuminated is 4 square meters, you can calculate the lux as follows:
Lux = 1000 lumens / 4 square meters Lux = 250 lux
In this example, the illuminance at a distance of 2 meters would be 250 lux.
Keep in mind that this calculation assumes that the light is evenly distributed over the entire illuminated area. If the light source has a narrower or wider beam angle, or if the distribution of light is not uniform, the lux value may vary across the surface being illuminated.
Lumens to lux calculation formula
Calculation with area in square feet
The illuminance Ev in lux (lx) is equal to 10.76391 times the luminous flux ΦV in lumens (lm) divided by the surface area A in square feet (ft2):
Ev(lx) = 10.76391 × ΦV(lm) / A(ft2)
For a spherical light source, the area A is equal to 4 times pi times the squared sphere radius:
A = 4⋅π⋅r 2
The illuminance Ev in lux (lx) is equal to 10.76391 times the luminous flux ΦV in lumens (lm) divided by 4 times pi times the squared sphere radius r in feet (ft):
Ev(lx) = 10.76391 × ΦV(lm) / (4⋅π⋅r(ft)2)
So
lux = 10.76391 × lumens / (square feet)
or
lx = 10.76391 × lm / ft2
Calculation with area in square meters
The illuminance Ev in lux (lx) is equal to the luminous flux ΦV in lumens (lm) divided by the surface area A in square meters (m2):
Ev(lx) = ΦV(lm) / A(m2)
For a spherical light source, the area A is equal to 4 times pi times the squared sphere radius:
A = 4⋅π⋅r 2
So the illuminance Ev in lux (lx) is equal to the luminous flux ΦV in lumens (lm) divided by 4 times pi times the squared sphere radius r in meters (m):
Ev(lx) = ΦV(lm) / (4⋅π⋅r(m) 2)
So
lux = lumens / (square meters)
or
lx = lm / m2
Example
What is the luminous flux on a surface of 4 square meters and illuminance of 500 lux?
ΦV(lm) = 500 lux × 4 m2 = 2000 lm
Lumens to lux Example
Assuming you have a light source with different luminous flux values in Lumens (lm) and you want to convert them to Lux (lx) at specific distances, you can use the following table:
| Luminous Flux (lm) | Distance (m) | Illuminance (lx) |
|---|---|---|
| 1000 | 1 | 1000 |
| 500 | 2 | 125 |
| 200 | 3 | 22.2 |
| 100 | 5 | 4 |
To calculate illuminance (lux), you need to consider the distance from the light source.
Divide the luminous flux by the product of the distance squared for each value to obtain the illuminance.
For example, if the luminous flux is 1000 lm and the distance is 1 meter, the illuminance would be (1000 lm) / (1^2 m^2) = 1000 lx.
Similarly, for a luminous flux of 500 lm and a distance of 2 meters, the illuminance would be (500 lm) / (2^2 m^2) = 125 lx.
You can follow the same calculation for other values in the table.
Please note that this calculation assumes an idealized point light source and that the light spreads uniformly in all directions. In practical scenarios, the actual illuminance may vary depending on the specific characteristics of the light source and the lighting environment.
