---
title: "Fresnel Reflection calculator — AperiOptic"
description: "Reflectance at normal incidence between two media. Free online optics calculator, with the formula and code snippets."
url: "https://aperioptic.com/calculators/fresnel-reflection"
---

# Fresnel Reflection calculator

Reflectance at normal incidence between two media.

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

Formula: `R = ((n₁-n₂)/(n₁+n₂))²`

## Inputs

| Input | Parameter | Unit | Default |
| --- | --- | --- | --- |
| n₁ | `n1` |  | 1 |
| n₂ | `n2` |  | 1.5 |

## Result with the default inputs

- Reflectance: 4 %
- Transmittance: 96 %

Open it with your own values: put each input in the address as a parameter, for example [`/calculators/fresnel-reflection?n1=1`](https://aperioptic.com/calculators/fresnel-reflection?n1=1). A unit other than the listed one goes in `<parameter>_unit`.

Read more: [Wikipedia: Fresnel equations](https://en.wikipedia.org/wiki/Fresnel_equations)

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

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