---
title: "Malus's Law calculator — AperiOptic"
description: "Transmitted intensity through a linear polarizer at angle θ. Free online optics calculator, with the formula and code snippets."
url: "https://aperioptic.com/calculators/maluss-law"
---

# Malus's Law calculator

Transmitted intensity through a linear polarizer at angle θ.

Category: [Polarization](https://aperioptic.com/calculators)

Formula: `I = I₀ · cos²(θ)`

## Inputs

| Input | Parameter | Unit | Default |
| --- | --- | --- | --- |
| Input I₀ | `I0` | W/m² | 1 |
| Angle θ | `theta` | deg | 30 |
| # polarizers | `n` |  | 1 |

## Result with the default inputs

- Transmitted I: 0.75 W/m²
- Transmission: 75%

Open it with your own values: put each input in the address as a parameter, for example [`/calculators/maluss-law?I0=1`](https://aperioptic.com/calculators/maluss-law?I0=1). A unit other than the listed one goes in `<parameter>_unit`.

Read more: [Wikipedia: Polarizer, Malus's law and other properties](https://en.wikipedia.org/wiki/Polarizer#Malus%27s_law_and_other_properties)

[All optics calculators](https://aperioptic.com/calculators)

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The interactive page: https://aperioptic.com/calculators/maluss-law (AperiOptic runs in the browser; free, no account). Every page of the site as Markdown: https://aperioptic.com/llms.txt