---
title: "Power ↔ dBm calculator — AperiOptic"
description: "Convert linear optical power to dBm and dBW. Free online optics calculator, with the formula and code snippets."
url: "https://aperioptic.com/calculators/power-dbm"
---

# Power ↔ dBm calculator

Convert linear optical power to dBm and dBW.

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

Formula: `dBm = 10·log₁₀(P/1 mW)`

## Inputs

| Input | Parameter | Unit | Default |
| --- | --- | --- | --- |
| Power | `P` | mW | 1 |

## Result with the default inputs

- Power: 1 mW
- Power: 1000 µW
- Power: 0.001 W
- dBm: 0
- dBW: -30

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

Read more: [Wikipedia: DBm](https://en.wikipedia.org/wiki/DBm)

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

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