Online Guitar Tuner & Chromatic Tuner

How to tune your instrument

Pick your instrument and tuning, press Start tuner and allow the microphone. Play one open string at a time and let it ring. The big letter is the string you are tuning, and the needle shows how far off it is:

• Needle left of centre (flat): tighten the string to raise the pitch.
• Needle right of centre (sharp): loosen it.
• Within 5 cents of the target the display turns green and the string gets a check mark.

The tuner picks the nearest string by itself. To stay on one string, press its button; press Auto to go back. Chromatic shows the nearest note of any sound, for instruments or tunings not in the list.

Tune up to the note rather than down to it: approaching from below leaves the string settled against the tuning peg, so it holds pitch longer. Tuning one string shifts the tension on the neck, so go over all the strings a second time, especially with a floating tremolo.

How the pitch is measured

The page runs the YIN pitch detection algorithm (de Cheveigné and Kawahara, 2002) on the most recent 4,096 samples, about 85 ms at 48 kHz. It compares the sound with delayed copies of itself; the delay at which it best matches itself is the period of the note. That window holds at least two periods of notes down to about 25 Hz, below the 30.87 Hz low B of a 5-string bass. The period is then refined on later repetitions, which makes a steady tone accurate to a fraction of a cent. A median filter and gentle smoothing keep the needle steady while a string decays.

Echo cancellation, noise suppression and automatic gain are switched off. Those filters are designed for speech and can treat a sustained note as noise to remove.

Cents and A4 calibration

A cent is 1/100 of an equal-tempered semitone, so an octave has 1,200. The offset from a target is 1200 × log2(heard ÷ target), and each note is A4 × 2^(n/12), where n counts semitones from A4. Differences of a few cents are hard to hear between single notes but show up as a slow beating when two strings sound together.

Match the calibration to the piano or recording you play with. Reference tones and targets follow it.

Standard tunings

Frequencies assume A4 = 440 Hz. Ukulele standard tuning is re-entrant: the G string is higher than the C next to it. Octave numbers are scientific pitch notation, where middle C is C4. French and Italian usage often numbers octaves one lower, so the note written La4 here may be called La3.

Reference tone plays the selected note through your speakers. The rich sound adds harmonics, so low bass notes stay audible on phone speakers that cannot reproduce 41 Hz.