Guitar and Ukulele Tuner

How to tune your guitar with the microphone

1. Choose your Instrument (Guitar, Ukulele or Bass guitar) and a Tuning. The buttons under String to tune show the target notes, numbered from the lowest string (for ukulele, in string order G C E A).
2. Press Start tuner and allow the microphone when your browser asks.
3. Play one open string at a time and let it ring. The big letter shows the Note you are playing, the needle shows how far you are from the target string, and the text tells you what to do: Too low: tune up (tighten), Too high: tune down (loosen) or In tune.
4. Turn the tuning peg slowly until the needle stays in the green zone in the centre (within ± 5 cents).
5. Repeat for each string, then check them all again: tuning one string slightly changes the tension on the others.

In Auto mode this tool picks the string closest to the note you play. If a string is very far off (for example a new string tuned a whole note low), click that string’s button so the tuner always compares with it. Play reference note plays the target pitch for two and a half seconds if you prefer to tune by ear.

The sound is analysed live in your browser and is never recorded or uploaded. Press Stop tuner to turn the microphone off.

Supported tunings

With the standard A4 = 440 Hz reference, the low E string of a guitar is 82.41 Hz and the high E is 329.63 Hz.

How the tuner works

The microphone signal goes to an analyser that captures about 90 ms of sound (about 180 ms for bass, whose low notes have long periods). A pitch detection algorithm based on autocorrelation (the McLeod Pitch Method, via the open-source pitchy library) finds the fundamental frequency and a clarity score. Readings with low clarity, such as noise or two strings at once, are ignored, and the median of the last five readings is shown to steady the needle.

The deviation is measured in cents, hundredths of a semitone: cents = 1200 × log2(f ÷ target). Five cents is close to the smallest difference a trained ear can hear between two successive notes.

Changing the A4 reference

Reference A4 (Hz) accepts values from 432 to 446 Hz. Keep 440 Hz unless you play with an instrument tuned differently: some orchestras tune to 442 or 443 Hz, and some musicians prefer 432 Hz. All strings move together, so the guitar stays in tune with itself.