---
title: "Radiation Pressure calculator — AperiOptic"
description: "Photon pressure on absorbing or perfectly reflecting surfaces. Free online optics calculator, with the formula and code snippets."
url: "https://aperioptic.com/calculators/radiation-pressure"
---

# Radiation Pressure calculator

Photon pressure on absorbing or perfectly reflecting surfaces.

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

Formula: `P_abs = I/c · P_refl = 2I/c`

## Inputs

| Input | Parameter | Unit | Default |
| --- | --- | --- | --- |
| Irradiance I | `I` | W/m² | 1000 |
| Spot side | `A` | mm | 1 |

## Result with the default inputs

- P (absorber): 3.3356e-6 Pa
- P (reflector): 6.6713e-6 Pa
- Force on A² (refl.): 0.0067 nN

Open it with your own values: put each input in the address as a parameter, for example [`/calculators/radiation-pressure?I=1000`](https://aperioptic.com/calculators/radiation-pressure?I=1000). A unit other than the listed one goes in `<parameter>_unit`.

Read more: [Wikipedia: Radiation pressure](https://en.wikipedia.org/wiki/Radiation_pressure)

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

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