Watts Lumens Candelas Converter
Convert light units for physically based 3D lighting setups.
Electrical power of the lamp
Total amount of light emitted
Intensity along the beam direction
Between 1 and 360 degrees
Conversion summary
60 W ≈ 800 lm ≈ 100 cd
Beam angle: 120°
Calculated parameters
13.3
lm/W
3.14
Solid angle (sr)
254.6
cd
Candelas = lumens / (2π × (1 − cos(θ/2))). Estimated LED efficacy: 13.5 lm/W.
What is a watts to lumens and candelas converter?
This converter relates the three units that define a physical 3D light: electrical power in watts (W), total luminous flux in lumens (lm) and luminous intensity in candelas (cd) according to the beam angle. It uses an estimated LED efficacy of 13.5 lm/W and the solid angle formula Ω = 2π(1 − cos(θ/2)) to derive the value you need.
How to use this tool
- Enter the power in watts (W) of your lamp if you know it.
- Add the luminous flux in lumens (lm) or leave it empty to derive it from watts.
- Adjust the beam angle in degrees to get the intensity in candelas.
- Leave empty the value you want to derive: the converter computes it instantly.
Typical use cases
- Set up physically based (PBR) lights in Blender with realistic LED bulb values.
- Convert manufacturer catalog specifications into scene parameters.
- Compute the intensity of a spot light for a specific beam angle.
Frequently asked questions
Which luminous efficacy is used to convert watts to lumens?
A conservative average of 13.5 lm/W is used. For greater accuracy, enter the real lumens of your bulb and leave the watts field empty.
How do candelas and lumens relate?
Candelas measure intensity in one direction: cd = lm / Ω, where Ω is the beam solid angle. A narrower beam concentrates the same light and produces more candelas.
What is the solid angle?
It is the portion of space covered by the beam, computed as Ω = 2π(1 − cos(θ/2)) for a cone of angle θ. It ranges from 0.0003 sr (1° beam) to 12.57 sr (full sphere of 360°).