Instrument Tuner

Tune any instrument with your microphone

This chromatic tuner listens to your instrument through the microphone and tells you exactly which note you are playing and how close you are to being in tune. It works for guitar, bass, violin, cello, ukulele, brass, woodwind and voice — anything that produces a clear pitched tone. Play a single note, let it ring, and the big letter shows the nearest note while the needle shows whether you are sharp or flat. When the needle rests in the centre at 0 cents, you are perfectly in tune.

The reading is based on the equal-tempered scale with A4 at 440 Hz, the standard concert pitch. Below the note you can see the detected frequency in hertz, so you can confirm, for example, that the open A string on a guitar is close to 110 Hz. Tune slowly and adjust in small steps; the needle responds in real time as the pitch changes.

How the pitch detection works

When you press start, the tool requests microphone access using getUserMedia and feeds the audio into the Web Audio API. An AnalyserNode captures short slices of the waveform, and an autocorrelation routine compares each slice against shifted copies of itself to find the repeating period of the wave. That period gives the fundamental frequency, which is then converted to the nearest note name and a cents offset. Autocorrelation is reliable for the steady, harmonic-rich tones that musical instruments produce, which is why it is a common choice for tuners.

Privacy and permissions

Microphone access only happens after you click start, and the browser will ask for permission the first time. The audio is processed live and is never recorded, stored or uploaded — all analysis runs locally in your browser. If the microphone fails to start, it is usually because the prompt was dismissed or blocked; you can re-enable it for this site in your browser's site settings and press start again. When you press stop, the microphone is released immediately.