Online Tuner (Guitar, Bass, Ukulele, Violin)

A tuner that listens to your instrument through the microphone and shows which note it is playing and how many cents sharp or flat it is. A cent is a hundredth of a semitone, and the needle reads as in tune within ±5 cents of the centre. The sound is analysed inside the browser only; nothing is recorded or sent anywhere.

Chromatic mode shows the nearest of the twelve notes, so it works for any instrument. Choose guitar (E2 A2 D3 G3 B3 E4), bass (E1 A1 D2 G2), ukulele (G4 C4 E4 A4) or violin (G3 D4 A4 E5) and it finds the nearest string of the standard tuning and compares against that string's target. Strings are numbered the usual way, with the highest as 1. The A4 reference can be set from 415 to 466 Hz, for orchestras that tune to 442 Hz or for baroque pitch at 415.

Pitch is found with the McLeod pitch method (the first clear peak of the normalised square difference function, refined by a parabola) about twelve times a second, and the median of the last five readings is shown so the needle stays steady. The browser's noise suppression and automatic gain are switched off so the waveform arrives untouched.

Play one string at a time and read it once the note settles rather than right after the pluck. A noisy room or several notes at once can make it lock onto a harmonic and read an octave high. It does not read below 35 Hz (which rules out a five-string bass's low B0) or above 1,400 Hz.