40 lux is equal to 40 lumens per square meter multiplied by the area in square meters. Without specifying the area, 40 lux itself cannot be directly converted to lumens, since lux measures illuminance (lumens per square meter). Assuming a 1 square meter area, 40 lux equals 40 lumens.
Lux measures the amount of light hitting a surface, while lumens measure the total light emitted. To convert lux to lumens, multiply the lux value by the surface area illuminated. Thus, if 40 lux illuminates 1 square meter, it corresponds to 40 lumens of light.
Conversion Tool
Result in lumens:
Conversion Formula
The conversion from lux to lumens depends on the area illuminated. Lux (lx) equals lumens (lm) divided by area in square meters (m²):
lux = lumens / area
To find lumens from lux, multiply lux by area:
lumens = lux × area
This works because lux measures the intensity of light on a surface, and lumens measures total light output. Without area, lux alone can’t convert to lumens. For example, if 40 lux shines on a 2 m² surface:
- Calculate lumens: 40 lx × 2 m² = 80 lumens
Conversion Example
- Example: Convert 30 lux on 3 square meters to lumens
- Multiply lux by area: 30 × 3 = 90 lumens
- So, 30 lux over 3 m² equals 90 lumens
- Example: Convert 50 lux on 0.5 square meters
- 50 × 0.5 = 25 lumens
- Therefore, 50 lux on half a square meter equals 25 lumens
- Example: Convert 60 lux on 4 square meters
- 60 × 4 = 240 lumens
- This means 60 lux illumination over 4 m² is 240 lumens
Conversion Chart
| Lux (lx) | Lumens (lm) at 1 m² |
|---|---|
| 15.0 | 15.0 |
| 25.0 | 25.0 |
| 35.0 | 35.0 |
| 45.0 | 45.0 |
| 55.0 | 55.0 |
| 65.0 | 65.0 |
This chart shows lux values converted to lumens assuming a surface area of 1 square meter. To find lumens for different areas, multiply the lux value in the chart by the desired surface area.
Related Conversion Questions
- How many lumens correspond to 40 lux over a 2 square meter surface?
- Can I convert 40 lux directly to lumens without knowing the area?
- What is the formula to calculate lumens from 40 lux?
- If a light source produces 40 lux, how much lumens does it emit on 5 m²?
- How does surface area affect converting 40 lux to lumens?
- Is 40 lux equal to 40 lumens for all surfaces?
- What is the difference between 40 lux and 40 lumens in lighting terms?
Conversion Definitions
Lux: Lux is a unit measuring illuminance, representing the amount of luminous flux hitting a surface area, given in lumens per square meter. It indicates how brightly a surface is lit, critical in lighting design and measurement.
Lumens: Lumens measure the total quantity of visible light emitted by a source. Unlike lux, lumens quantify light output without considering the area it spreads over, providing a way to compare brightness of bulbs or lamps.
Conversion FAQs
Why can’t lux be converted to lumens without knowing the area?
Lux measures illuminance, or light per unit area, so its value depends on how big the surface is. Lumens measures total light output regardless of area. Without the surface area, conversion isn’t possible because lumens = lux × area.
Does increasing the surface area increase lumens if lux stays constant?
Yes, if illuminance (lux) remains the same but the illuminated area grows, the total light output in lumens increases proportionally since lumens equals lux times area.
Can I use the conversion formula for curved or irregular surfaces?
The formula assumes flat surfaces; for curved or uneven surfaces, effective area calculations become complex, and simple multiplication may not be accurate for lumens estimation.
How does distance from light source affect lux and lumens?
Distance impacts lux since illuminance decreases with distance squared, but lumens emitted by the source remain constant. So lux changes with distance, lumens do not.
Is it possible for two lights with same lumens to produce different lux values?
Yes, because lux depends on both lumens and area illuminated. Two lamps with identical lumens can produce different lux if their light spreads differently or illuminates distinct surface sizes.