How to use it
- Choose your instrument and tuning (standard guitar is E2 A2 D3 G3 B3 E4, low to high), or Chromatic for any note. Press Start tuner and allow the microphone.
- Play one string and let it ring. The big letter is the string the tuner thinks you are tuning; the needle and the number show how far off you are in cents (a hundredth of a semitone).
- “Too low” means tighten the string (tune up), “too high” means loosen it. The note turns green within 5 cents. If the tuner picks the wrong string because you are far out, tap that string’s button to lock it.
How it finds the pitch
The tuner uses YIN, a pitch-detection method published by Alain de Cheveigné and Hideki Kawahara in 2002. It compares each 85 ms block of sound (4,096 samples) with copies of itself shifted in time, finds the smallest shift at which the sound repeats, and refines that shift between samples. A guitar string’s overtones can be stronger than its fundamental, which is where simpler methods jump an octave; YIN’s normalisation step is designed to avoid that. The note is then named in equal temperament from the reference pitch: a note n semitones above A4 has the frequency 440 × 2n/12 Hz. The tuner shows the median of its last five readings, about 0.4 seconds, so the needle does not jitter as a string decays.
It opens the microphone with the browser’s noise suppression, echo cancellation and gain control switched off. That matters: in our Mic Test measurements, Chrome’s noise suppression cut a steady tone by almost 20 dB, because a held note looks like background noise.
How accurate it is
We ran the page’s own pitch function on synthetic notes from E1 (41 Hz, a bass’s low E) to C6 (1,047 Hz): every semitone plus random detunings, 228 notes for each kind of sound. Median errors: pure tone 0.012 cents, a bright sawtooth 0.008, a plucked string 0.01, a tone with its fundamental removed 0.012; 95% of readings were within 0.34 cents or better in each of those, and none named the wrong note or octave. With noise mixed in at 20 dB below the note the median was 0.241 cents and the worst 4.783. A version without the between-sample refinement was off by up to 8 to 12 cents in 5% of readings. For scale, ISO 16 sets concert A at 440 Hz and asks tuning instruments to produce it within 0.5 Hz, about 2 cents. Real accuracy also depends on your microphone, the room and a string that rings cleanly; play near the microphone and avoid touching the other strings.
In Chromium we also played plucked-string recordings through a virtual microphone: an A2 string 12 cents flat read −12.0 cents with “Too low: tighten (tune up)”, an in-tune low E read 0.0, a high E 20 cents sharp read +20.0 (on a 390 px screen), and chromatic mode named a 466.16 Hz note A♯4.
Tunings included
Guitar standard (E A D G B E), drop D (D A D G B E), half step down (E♭ A♭ D♭ G♭ B♭ E♭, shown as sharps), open G (D G D G B D), 4-string bass (E1 A1 D2 G2) and ukulele (G4 C4 E4 A4, re-entrant high G). The reference A can be set from 415 to 466 Hz to match another instrument or a recording.
Sources
- Alain de Cheveigné and Hideki Kawahara, YIN, a fundamental frequency estimator for speech and music, Journal of the Acoustical Society of America 111(4), 2002.
- ISO, ISO 16:1975 Acoustics — Standard tuning frequency (A = 440 Hz, within 0.5 Hz; confirmed 2022).
Frequently Asked Questions
Built by Derek Giordano · Part of Ultimate Design Tools