Lumens ↔ Millicandela
Convert between luminous flux and luminous intensity
Understanding the Conversion
Lumens (lm) and millicandela (mcd) are both units of luminous measurement, but they represent different aspects of light:
Lumens (lm) measure total luminous flux (total light output in all directions)
Millicandela (mcd) measures luminous intensity (brightness in a specific direction)
When is this conversion needed?
Comparing LED brightness specifications
Matching light sources for directional lighting
Understanding flashlight or spotlight beam intensity
Conversion Formula
The conversion depends on the beam angle of the light source:
Where:
θ = Beam angle in degrees
1,000,000 converts candela to millicandela
2π(1-cos(θ/2)) calculates the solid angle in steradians
Common Beam Angles and Their Conversions
| Beam Angle | Conversion Factor (lm → mcd) |
|---|---|
| 15° | 1 lm ≈ 170,000 mcd |
| 30° | 1 lm ≈ 42,000 mcd |
| 45° | 1 lm ≈ 18,000 mcd |
| 60° | 1 lm ≈ 9,500 mcd |
| 90° | 1 lm ≈ 4,200 mcd |
| 120° | 1 lm ≈ 2,100 mcd |
Calculator Tool
Enter your values:
Lumens: [_____] lm
Beam angle: [_____] degrees
Result:
Millicandela: [calculated value] mcd
Example Calculation
For a 100 lumen LED with 30° beam angle:
100 lm × 42,000 (conversion factor) = 4,200,000 mcd
Important Notes
This conversion is only accurate for uniform point sources
Real-world LEDs may vary due to manufacturing differences
For non-uniform beams, consult the manufacturer's specifications