About

Sound Decibel Meter is a free tool for checking how loud your surroundings are. Open the page, allow the microphone, and you get a live decibel reading with peak, minimum and average levels for the session. There is nothing to install and no account to create.

Why a browser-based meter?

Most people who want to know whether a room, a café, a workshop or a concert is loud do not own a sound level meter. They do own a phone or a laptop with a microphone. The Web Audio API lets a web page read that microphone and compute loudness in real time, so the meter can live at a URL instead of in an app store.

How it works

The page captures raw audio from your microphone with echo cancellation, noise suppression and automatic gain turned off, so the signal is as untouched as the browser allows. It computes the root-mean-square level of the signal many times per second, applies a fast 125 millisecond time weighting like a hand-held meter, and converts the result to decibels with a device offset you can adjust. The whole process runs on your device. Nothing is recorded or uploaded.

Limits

Consumer microphones are not calibrated instruments, so readings are estimates. The site is honest about that rather than pretending otherwise. See the disclaimer for what the tool should not be used for.

Get in touch

Suggestions and bug reports are welcome on the contact page.