Lumen Calculator

Lumen Calculator

Convert between Lumens, Lux, and Candela based on distance and beam angle.

Last updated: March 2026 | By ForgeCalc Engineering

Illuminance (Lux)
79.58
Luminous Intensity (Candela)
318.31

Lumens vs Lux vs Candela

Lumens (lm)

The total amount of light emitted by a source in all directions. It measures the "quantity" of light.

Lux (lx)

The amount of light hitting a specific surface area. 1 Lux = 1 Lumen per square meter.

Candela (cd)

The intensity of light in a specific direction. It accounts for the beam angle of the light source.

The Math Behind Light

Steradians Formula

Ω = 2π * (1 - cos(θ/2))

Lux Formula

Lux = Lumens / (Ω * d²)

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