💡 Lumen Calculator (Lumen to Lux to Candela)
Convert lumens to candela and lux based on beam angle and distance from the light source.
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From Lumens to Candela and Lux
Lumens measure the total light a source emits, but how bright it looks depends on how tightly that light is focused and how far away you are. This calculator first converts lumens to candela (luminous intensity) using the beam’s solid angle: candela = lumens ÷ Ω, where Ω = 2π(1−cos(θ/2)) is the solid angle of a cone with full beam angle θ.
It then applies the inverse-square law, lux = candela ÷ distance2, to find the illuminance at your chosen distance. Narrower beam angles concentrate the same lumens into higher candela and higher lux at a given distance.
Last reviewed August 2026