Malus's Law (Polarisers)

Calculate the light intensity transmitted through one or two polarising filters at a given angle, free online.

Incident intensity I₀

Angle between polariser axes (°)

Incident light

About this calculator

Malus's law: I = I₀ cos²θ for polarised light hitting an analyser at angle θ. Unpolarised light loses half its intensity passing through the first polariser (I = I₀/2) before Malus's law applies to the next one.