Candela → Lumen
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The Candela → Lumen calculator converts luminous intensity (candela) to total luminous flux (lumen), considering the light source's solid angle. Candela measures intensity in a specific direction, while lumen quantifies the total light emitted in all directions. The formula used is: Lumen = Candela × Solid Angle (in sr). This helps evaluate lamps, LEDs, or headlights for lighting projects.
This conversion is practical for lighting design, such as selecting bulbs for indoor or outdoor spaces. For example, a lamp rated at 1000 candelas with a 1 sr solid angle emits 1000 lumens. If the angle doubles (2 sr), the flux doubles. The calculation allows comparing products with different technical specifications effectively.
Note: Solid angle must be precisely known. Directional light sources (like flashlights) have smaller angles, while omnidirectional bulbs have larger angles (4π sr). Inaccurate angle values lead to flawed conversions. Always refer to equipment manuals or use professional measurement tools for exact data.
Frequently asked questions
What is the difference between candela and lumen?
Candela measures light intensity in a specific direction, while lumen measures total light output in all directions.
How does the calculator perform the conversion?
It multiplies candelas by the source's solid angle in steradians (sr). E.g.: 500 cd × 2 sr = 1000 lm.
When should this conversion be used?
For lighting projects, such as comparing bulb efficiency or adjusting store or street lighting.
Can I convert lumen to candela directly?
No, you need the solid angle: Candela = Lumen ÷ Solid Angle.