1 lumen equals 1 lux when the luminous flux is uniformly distributed over an area of 1 square meter.
Lux measures illuminance, which depends on the amount of light (lumens) spread over a surface area. Since 1 lux is defined as 1 lumen per square meter, converting 1 lumen directly to lux assumes the light covers exactly 1 square meter.
Conversion Tool
Result in lux:
Conversion Formula
The formula for converting lumen to lux is:
lux = lumen / area (in square meters)
This works because lux measures illuminance, which is the luminous flux (in lumens) divided by the surface area it shines upon. When 1 lumen is spread over 1 square meter, it equals 1 lux.
For example:
- If you have 5 lumens of light spread over 2 square meters, then lux = 5 / 2 = 2.5 lux.
- If 10 lumens spread over 5 square meters, lux = 10 / 5 = 2 lux.
Conversion Example
- Convert 3 lumens to lux over 1 square meter:
- Since area is 1 m², lux = 3 / 1 = 3 lux.
- So, 3 lumens equals 3 lux.
- Convert 8 lumens over 4 square meters:
- lux = 8 / 4 = 2 lux.
- Meaning 8 lumens distributed over 4 m² results in 2 lux illuminance.
- Convert 12 lumens over 3 square meters:
- lux = 12 / 3 = 4 lux.
- So the illuminance is 4 lux.
- Convert 0.5 lumens over 0.5 square meters:
- lux = 0.5 / 0.5 = 1 lux.
- Even small values follows same formula.
Conversion Chart
| Lumen | Lux (assuming 1 m² area) |
|---|---|
| -24.0 | -24.0 |
| -23.0 | -23.0 |
| -22.0 | -22.0 |
| -21.0 | -21.0 |
| -20.0 | -20.0 |
| -19.0 | -19.0 |
| -18.0 | -18.0 |
| -17.0 | -17.0 |
| -16.0 | -16.0 |
| -15.0 | -15.0 |
| -14.0 | -14.0 |
| -13.0 | -13.0 |
| -12.0 | -12.0 |
| -11.0 | -11.0 |
| -10.0 | -10.0 |
| -9.0 | -9.0 |
| -8.0 | -8.0 |
| -7.0 | -7.0 |
| -6.0 | -6.0 |
| -5.0 | -5.0 |
| -4.0 | -4.0 |
| -3.0 | -3.0 |
| -2.0 | -2.0 |
| -1.0 | -1.0 |
| 0.0 | 0.0 |
| 1.0 | 1.0 |
| 2.0 | 2.0 |
| 3.0 | 3.0 |
| 4.0 | 4.0 |
| 5.0 | 5.0 |
| 6.0 | 6.0 |
| 7.0 | 7.0 |
| 8.0 | 8.0 |
| 9.0 | 9.0 |
| 10.0 | 10.0 |
| 11.0 | 11.0 |
| 12.0 | 12.0 |
| 13.0 | 13.0 |
| 14.0 | 14.0 |
| 15.0 | 15.0 |
| 16.0 | 16.0 |
| 17.0 | 17.0 |
| 18.0 | 18.0 |
| 19.0 | 19.0 |
| 20.0 | 20.0 |
| 21.0 | 21.0 |
| 22.0 | 22.0 |
| 23.0 | 23.0 |
| 24.0 | 24.0 |
| 25.0 | 25.0 |
| 26.0 | 26.0 |
This chart shows lumen values converted directly to lux assuming the light is spread evenly over 1 square meter area. To use, find the lumen value and read corresponding lux in the adjacent column. Negative values imply negative luminous flux, which is physically uncommon but shows mathematical relation.
Related Conversion Questions
- How many lux corresponds to 1 lumen if area changes?
- What is the lux value for 1 lumen over 0.5 square meters?
- Does 1 lumen always equal 1 lux?
- How to convert 1 lumen to lux in outdoor lighting?
- What area is needed for 1 lumen to equal 1 lux?
- Can I use lumen to lux conversion for LED lights?
- Why does 1 lumen not equal 1 lux sometimes?
Conversion Definitions
Lumen: Lumen is a measure of luminous flux, quantifying the total visible light emitted by a source. It describes how much light is produced, without considering the direction or area coverage. Higher lumens means brighter light, regardless of spread or distance.
Lux: Lux measures illuminance, which is the amount of luminous flux spread over a given area, calculated in lumens per square meter. It indicates how brightly a surface is illuminated, factoring light intensity and surface size.
Conversion FAQs
Why does converting 1 lumen to lux require knowing the area?
Because lux is defined as lumens per square meter, without knowing the area over which light spreads, you can’t determine illuminance. One lumen spread over 1 m² equals 1 lux, but if spread over 2 m², lux halves. Area directly affects illuminance values.
Can lux ever be greater than lumen?
No, lux cannot exceed lumen because lux measures luminous flux per unit area. If luminous flux stays constant but area decreases, lux increases, but total lumens remain the same. So, lux can be higher numerically for smaller areas, but total lumens emitted don’t change.
Is it correct to say 1 lumen equals 1 lux always?
No, it’s only true if the 1 lumen is uniformly distributed over exactly 1 square meter. Changing area changes lux accordingly. Without specifying surface area, the conversion can’t be exact.
How does distance affect lumen to lux conversion?
Distance changes the area illuminated, so lux changes even if lumens remain constant. As distance grows, light spreads over larger area, reducing lux. Lumens measure total emitted light, lux measures intensity on surface, so distance is crucial.
Why are some lumen to lux conversions negative values shown?
Negative lumens or lux are physically unrealistic but may appear in calculations or charts to represent errors, hypothetical data, or mathematical continuity. In real terms, luminous flux and illuminance can’t be negative.