Calculate total light output (lumens) from intensity (candela) and beam angle.
Light Source Parameters
lm
°
m
Lighting Results
Enter light data to see results
About this calculator
Quick Reference
Ω (Solid Angle)Steradians (sr)
cd (Candela)Luminous Intensity
lm (Lumen)Luminous Flux
Luxlm / m²
Overview
Lumens measure the total amount of light emitted by a source in all directions, while Candelas measure the intensity of light in a specific direction. The relationship between them depends on how narrow or wide the beam of light is.
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Pro Tips
A 100W incandescent bulb produces about 1,600 lumens.
Candela = Lumens / Solid Angle (Ω).
Ω = 2π * [1 - cos(θ/2)], where θ is the beam angle.
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Fun Facts
"Wait, did you know that the 'Candela' was originally based on the light from a real, standard candle? That's why one candela is roughly the intensity of one common candle."
"The moon has a very high 'luminosity' but low 'albedo' (it's actually quite dark, like asphalt), but looks bright against the black of space."
"High-power laser pointers have very few lumens (often less than 5), but extremely high candela because all that light is packed into a tiny, tiny angle."
