Lumen → Candela
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
This calculator converts lumens (lm) to candelas (cd) using the formula cd = lm / (4π·sr), assuming uniform light distribution in all directions (4π steradians). Lumens measure total light output, while candelas quantify intensity in a specific direction. For accurate conversions, divide lumens by 4π (approximately 12.566) to obtain candelas.
It’s commonly used in lighting design, LED development, or light source analysis. For example, a lamp emitting 1000 lm uniformly would have an intensity of ~79.6 cd (1000 / 12.566). Avoid using it directly for non-uniform distributions (e.g., directional spotlights), as the formula assumes isotropic emission.
Note: results depend on emission patterns. If light is focused into an angle smaller than 4π (like car headlights), the formula won’t apply. For irregular distributions, consult beam angle tables or use directional sensors.
Frequently asked questions
What distinguishes lumens from candelas?
Lumens measure total light output in all directions, while candelas quantify intensity per steradian in a specific direction.
When should I use this calculator?
Use it to convert uniformly emitting sources (like spherical lamps) to candelas, common in technical specifications for lighting.
Why divide by 4π?
4π represents steradians in a full sphere (360° in all directions). This formula assumes even 3D light distribution.
Can it be used for directional LEDs?
No, since LEDs typically emit light in angles smaller than 4π. Check the manufacturer's beam angle for accurate conversions.