Photometry Tools

Candela to Lumens Calculator

Convert luminous intensity in candelas (cd) to overall luminous flux output in lumens (lm).

Calculation Input

Calculated Output Flux

0.00 lm

Solid Angle (Steradians) 0.00 sr

Beam Angle Type Narrow Spot

How Luminous Flux is Calculated

Candelas ($cd$) measures the light intensity in a specific spatial direction, whereas lumens ($lm$) measures the total light flux emitted in all directions. To convert from candela to lumens, we multiply the directional intensity by the solid angle ($\Omega$, measured in steradians) representing the coverage cone:

$$lm = cd \times 2\pi \left(1 - \cos\left(\frac{\theta}{2}\right)\right)$$

Where $\theta$ is the apex beam angle in degrees. The solid angle $\Omega = 2\pi(1 - \cos(\theta/2))$.