Lumen to Lux Calculator
Convert lumens to lux with step-by-step calculations. Perfect for lighting design, illuminance planning, and photometric calculations.
Luminous Flux to Illuminance Converter
Common Lumen to Lux Conversions
Click on these links to see instant conversions with common values:
Understanding Lumen to Lux Conversion
Converting lumens to lux involves dividing total light output by the illuminated area. This conversion is essential for understanding how bright a surface will appear under different lighting conditions.
Conversion Formulas
lux = lumens ÷ area (m²)
Point Source Method:
lux = lumens ÷ (4π × distance²)
Where:
• lux = illuminance (light per unit area)
• lumens = luminous flux (total light output)
• area = illuminated surface area (m²)
• distance = distance from point source (m)
Key Concepts
- Lumens (lm): Total luminous flux - the total amount of visible light emitted
- Lux (lx): Illuminance - the amount of light falling on a surface per unit area
- Area Distribution: Same lumens spread over larger areas results in lower lux
- Point Source: For point lights, use distance-based calculation with 4π factor
Recommended Illuminance Levels
| Application | Recommended Lux | Example Area | Required Lumens |
|---|---|---|---|
| Bedroom (ambient) | 100-150 | 12 m² | 1200-1800 lm |
| Living Room | 150-300 | 20 m² | 3000-6000 lm |
| Kitchen (general) | 200-400 | 15 m² | 3000-6000 lm |
| Office Work | 300-500 | 10 m² | 3000-5000 lm |
| Task Lighting | 500-1000 | 1 m² | 500-1000 lm |
| Detailed Work | 1000-2000 | 1 m² | 1000-2000 lm |
Frequently Asked Questions
How do you convert lumens to lux?
Divide lumens by the illuminated area: lux = lumens ÷ area (m²). For point sources, use lux = lumens ÷ (4π × distance²). The area or distance determines how concentrated the light is.
Why do you need area or distance for lumen to lux conversion?
Lux is lumens per square meter (lm/m²). The same lumen output spread over different areas results in different lux levels - larger areas have lower lux for the same total lumens.
What's the difference between direct area and point source methods?
Direct area method divides lumens by actual illuminated area. Point source method uses distance from a theoretical point light, accounting for light spreading in all directions (4π steradians).