Guitar tuner
Play a string and bring the needle to the middle.
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The sound is analysed here in your browser — nothing is recorded or sent.
440 Hz
How to tune your guitar online
Press "Start tuner" and allow the microphone when your browser asks. Play one open string at a time and let it ring. The dial shows how far off you are in cents: tighten the string if the needle sits left of centre (flat), loosen it if it sits right (sharp). Once the note holds within 3 cents, the "In tune" stamp lands.
In Auto, the tuner lights up the nearest string by itself. If a string is far off — a new set of strings, or a different tuning — tap that string instead, and the tuner aims for it however far away you start.
Tunings and reference pitch
It knows Standard, Drop D, Half step down, DADGAD and Open G. The reference pitch is A4 = 440 Hz by default and goes from 432 to 446 Hz, for playing along with a recording or a band that tunes a little high or low.
Questions
Does the tuner record or upload my sound?
No. The sound is analysed in your browser while the tuner is on, and never leaves your device. The microphone is only opened when you press "Start tuner", and closed when you stop.
Does it work for acoustic and electric guitar?
Yes. An acoustic is picked up by the microphone directly; for an electric, play it through an amp near the computer or phone, or unplugged close to the microphone.
Can I use it on my phone?
Yes — it works in any modern mobile browser. Allow the microphone when asked, and hold the phone close to the guitar.