Online tuner for guitar, bass, ukulele, mandolin and banjo

• Allow microphone access in your browser. Nothing to install, and nothing leaves your device: the analysis runs locally.
• Pick the mode matching your instrument. The mode narrows detection to a tight range around the expected strings, which rules out mains hum and high-frequency noise.
• Play an open string and let it ring: a sustained note measures far better than a sharply plucked one.
• Bring the needle to zero. The scale is graduated in cents, from −50 to +50.
• Work from the lowest string to the highest, then go round again: changing one string changes the tension on the neck, so the others drift slightly.

One detail that prevents a lot of mistakes: in instrument mode, a frequency detected an octave away is folded back onto the right string. You cannot tune a string a full octave too high without noticing — the classic trap of chromatic tuners.

These values are not copied from a table: they are computed from the 440 Hz reference A using equal temperament. They are exactly the targets the tuner aims for.

The guitar offers three alternative tunings alongside standard: drop D, half a step down, and open G. The other instruments use standard tuning; for anything else, chromatic mode still works.

Chromatic mode listens from 40 to 1,500 Hz and shows the nearest note, without assuming a target string. It comes in handy whenever the instrument is not on the list: voice, harmonica, brass, strings deliberately tuned off standard, or simply to check a pitch.

A semitone is 100 cents, so the scale covers one semitone either side of the target note. Beyond fifty cents the tuner switches to the neighbouring note: if the note shown is not the one you expect, you are more than a semitone off.

A piece of luthier advice that holds for every string instrument: arrive at the note from below. A string loosened and then brought up holds its tuning far better than one overtightened and released.