Lumens to candela calculator

Lumens (lm) to candela (cd) calculator and how to calculate.

Enter the luminous flux in lumens, apex angle in degrees and press the Calculate button to get the luminous intensity in candela:

For uniform, isotropic light source, the luminous intensity I_v in candela (cd) is equal to the luminous flux Φ_vin lumens (lm),

divided by the solid angle Ω in steradians (sr):

I_v(cd) = Φ_v(lm) / Ω_(sr)

The solid angle Ω in steradians (sr) is equal to 2 times pi times 1 minus cosine of half the cone apex angle θ in degrees (º):

Ω_(sr) = 2π(1 - cos(θ/2))

The luminous intensity I_v in candela (cd) is equal to the luminous flux Φ_vin lumens (lm),

divided by 2 times pi times 1 minus cosine of half the apex angle θ in degrees (º):

I_v(cd) = Φ_v(lm) / ( 2π(1 - cos(θ/2)) )

candela = lumens / ( 2π(1 - cos(degrees/2)) )

cd = lm / ( 2π(1 - cos(º/2)) )

See also

Enter luminous flux in lumens:		lm
Enter apex angle in degrees:		º

Luminous intensity result in candela:		cd