15 lumens converted to lux depends on the area over which the light is spread. Assuming the light is uniformly spread over 1 square meter, 15 lumens equals 15 lux.
Lux measures illuminance, which is lumens per square meter. So, if 15 lumens is spread across 1 square meter, the lux value will be 15. If the area changes, the lux value changes inversely.
Conversion Tool
Result in lux:
Conversion Formula
The conversion from lumens to lux depends on the area the light covers. Lux equals lumens divided by area in square meters:
Lux = Lumens / Area (m²)
This formula works because lumens measure total light output, while lux measures light intensity per area. So, spreading lumens over larger space decreases lux.
For example, if you have 15 lumens lighting 1 square meter:
- Lux = 15 lumens / 1 m²
- Lux = 15
If the same 15 lumens is spread over 3 square meters:
- Lux = 15 lumens / 3 m²
- Lux = 5
Conversion Example
- Convert 30 lumens to lux on 1 m² area:
- Lux = 30 / 1 = 30 lux
- The light intensity is 30 lux on that area.
- Convert 50 lumens to lux over 5 m²:
- Lux = 50 / 5 = 10 lux
- Since area increased, lux decreased.
- Convert 100 lumens to lux on 0.5 m²:
- Lux = 100 / 0.5 = 200 lux
- Smaller area means higher lux value.
- Convert 0 lumens to lux on any area:
- Lux = 0 / area = 0 lux
- No light output means no illuminance.
Conversion Chart
| Lumens | Lux (1 m² area) |
|---|---|
| -10.0 | -10.0000 |
| -5.0 | -5.0000 |
| 0.0 | 0.0000 |
| 5.0 | 5.0000 |
| 10.0 | 10.0000 |
| 15.0 | 15.0000 |
| 20.0 | 20.0000 |
| 25.0 | 25.0000 |
| 30.0 | 30.0000 |
| 35.0 | 35.0000 |
| 40.0 | 40.0000 |
To use this chart, find the lumens value in first column, then look right to see lux assuming light spread over 1 square meter. Negative lumens are physically impossible but shown here for completeness.
Related Conversion Questions
- How many lux does 15 lumens produce on 2 square meters?
- What is the lux value if 15 lumens spread over 0.75 m²?
- Can 15 lumens provide enough lux for reading light?
- How do I calculate lux from 15 lumens in an outdoor setting?
- What lux does a 15-lumen bulb create in a 5 m² room?
- Is 15 lumens equal to 15 lux always?
- How does surface area affect lux when I have 15 lumens?
Conversion Definitions
Lumens: Lumens measure the total quantity of visible light emitted by a source per unit time. It quantifies the perceived power of light to the human eye, independent of direction or area, differing from watts which measure energy consumption.
Lux: Lux is the unit of illuminance, describing how much luminous flux falls on a square meter of surface. It tells how bright the surface appears, calculated by dividing lumens by area in square meters, reflecting intensity rather than total light output.
Conversion FAQs
Why does lux depend on area when converting from lumens?
Because lumens measure total light emitted, lux measures how concentrated that light is on a surface. If you spread the same lumens over a larger area, the light becomes less intense per square meter, reducing lux. So, lux varies inversely with area size.
Can I convert lumens to lux without knowing the illuminated area?
No, without the area size, you can’t accurately convert lumens to lux. Lumens alone tell total light output, but lux needs how much space that light covers. Assuming 1 square meter is common but not accurate if area differs.
Is it possible to have negative lumens or lux values?
Negative lumens or lux have no physical meaning, since light output and illuminance can’t be less than zero. Negative values may appear in calculations or data errors but are invalid in real-world lighting measurements.
Does lux measure light intensity or brightness?
Lux measures illuminance, which correlates to light intensity on a surface. Brightness perception depends on human eye response and context, but lux quantifies the actual physical amount of light falling per unit area.
How accurate is the simple lumens to lux formula in practical scenarios?
The formula Lux = Lumens / Area applies when light spreads evenly on a flat surface. In real situations, factors like reflection, angle, and distance affect lux, so actual measurements may vary from simple calculations.
Last Updated : 04 July, 2025
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Sandeep Bhandari holds a Bachelor of Engineering in Computers from Thapar University (2006). He has 20 years of experience in the technology field. He has a keen interest in various technical fields, including database systems, computer networks, and programming. You can read more about him on his bio page.