Guitar Tuner

How to use

1. 1Pick an instrument and tuning from the menu (Guitar standard EADGBE, Drop D, DADGAD, Bass 4 or 5 string, Ukulele, Mandolin, Violin, and more).
2. 2Set the A4 concert-pitch reference. 440 Hz is the modern default; pick 432, 442, 444, or 415 Hz for alternate, orchestral, or Baroque tunings.
3. 3Press Start microphone and grant permission. The browser will ask once; the OS recording indicator will turn on while the tuner is listening.
4. 4Play a single sustained note on one string. Watch the needle and the cents readout: inside +/- 5 cents is in tune, flat means tune up, sharp means tune down.
5. 5If the microphone is not available or you prefer to tune by ear, tap any string in the Reference tones panel to play its exact target pitch through your speakers.
6. 6Press Stop microphone when finished to release the device and turn off the OS recording indicator.

About this tool

Guitar Tuner is a free chromatic instrument tuner that runs entirely in your browser. It offers two complementary ways to tune. The microphone tuner uses navigator.mediaDevices.getUserMedia and the Web Audio API to capture short windows of audio from the device microphone, then runs a YIN-style autocorrelation algorithm on the raw time-domain samples to detect the fundamental pitch of whatever is plucked, strummed, or bowed. The detected frequency is mapped to the closest 12-tone equal-temperament note (using a configurable A4 reference, 440 Hz by default, with 432, 442, 444, and 415 Hz also available for orchestral, period, and baroque tunings) and the deviation is shown in cents on a -50 to +50 needle meter. One cent is one hundredth of a semitone, so anything inside +/- 5 cents is considered in tune; the needle shifts to green at that point and the matched string in the tuning list is highlighted. The reference-tone player provides a clean fall-back: tap any string in the active tuning to play its exact target pitch through your speakers and tune by ear. Tunings included cover guitar standard EADGBE, Drop D, Drop C, Half-step down (Eb), DADGAD, Open G, Open D, and Open C, plus 4-string and 5-string bass, ukulele standard GCEA (high-G reentrant), mandolin GDAE, and violin GDAE. Pitch detection runs on 2048-sample buffers so the lowest string of a 5-string bass (low B at about 31 Hz fundamental) and the highest violin E (about 2637 Hz) are both inside the searched range. To make detection on stringed instruments more reliable than the speech-tuned defaults browsers apply for voice calls, the tuner explicitly turns off noiseSuppression, echoCancellation, and autoGainControl when it requests the microphone, so the raw signal reaches the analyzer. Cents readings are smoothed with a small exponential moving average so the needle does not jitter while a string is still ringing, and readings below the YIN confidence threshold are rejected so silence and noise do not produce phantom notes. The microphone is connected to the analyzer but never to the audio destination, so there is no feedback risk when tuning over speakers. Audio never leaves your device; no recording, no upload, no signup. Useful for tuning an acoustic or electric guitar, a bass, a ukulele, a mandolin, or a violin without installing an app, for setting up alternate tunings before practice, for tuning to alternate concert-pitch references (432, 442, 444, 415 Hz), and for any quick check on the road. Stop the microphone with the Stop microphone button and the OS recording indicator will turn off.

Free to use. Works in your browser. No signup, no login.