About Online Tuner

Online Tuner is a free tuner for guitar, ukulele, violin, bass, wind instruments and voice. It runs entirely in your browser and is made by Appcellent, a small studio that builds measurement and music tools.

How pitch detection works

The tuner reads short blocks of sound from your microphone many times per second and finds the fundamental frequency with the YIN algorithm (de Cheveigné and Kawahara, 2002), which is designed to avoid octave mistakes when overtones are louder than the fundamental note. A short median filter steadies the reading before the needle moves.

We test the detector two ways. First on generated tones from a 5-string bass low B (B0) up to C6, at 44.1, 48 and 96 kHz, including tones with a weak fundamental, mains hum and room noise. Second on 58 studio recordings of 11 instruments (violin, viola, cello, double bass, guitar, flute, clarinet, trumpet, alto saxophone, trombone and French horn) from the University of Iowa Musical Instrument Samples, run through the same code the browser uses. In that check, at normal playing volume, the tuner showed the right note or string on about 95% of the frames where an instrument is sounding, and a wrong note on fewer than 1%. We used the same recordings to find and fix problems, so treat this as a sanity check rather than an independent benchmark; very quiet (pianissimo) playing is read less often. Your own microphone and room add noise, so results also depend on your device.

Notes and frequencies

Every frequency on this site is calculated with twelve-tone equal temperament: f = 440 × 2^{(n − 69) / 12}, where n is the MIDI note number and A4 = 440 Hz. Octave numbers follow scientific pitch notation (middle C = C4). You can change the reference pitch under the tuner.

Privacy

The microphone signal is processed on your device and is never recorded or uploaded. See the privacy policy.

Contact

Questions, a tuning you would like added or a bug: support@onlinetuner.app.