Online Guitar Tuner

Click Start Tuning and allow microphone access when your browser asks. Pick the string you want to tune, play it open, and watch the meter: the needle sits left of center when the string is flat (too low) and right of center when it's sharp (too high). Turn the tuning peg slowly until the needle settles in the green zone. Tune one string at a time, from the low E up to the high E, then quickly recheck them all — tightening one string can slightly change the others.

Too low (flat) means the string vibrates below the target pitch — tighten it by turning the peg so the pitch rises. Too high (sharp) means it's above the target — loosen it. If you overshoot, it's good practice to tune down below the note and come back up to it; strings hold tune better when the last peg movement was upward. The tuner shows the offset in cents: 100 cents equals one semitone, so a reading of +20¢ means you're a fifth of a semitone sharp.

This tuner shows green when you're within 5 cents of the target pitch, which is tighter than most players can hear. Don't chase a perfectly still needle — a plucked string naturally starts slightly sharp and settles as it rings, so judge the reading after the first moment of the pluck. Anything inside the green zone will sound in tune with other instruments tuned to the same A4 = 440 Hz reference.

Standard tuning for a six-string guitar is E-A-D-G-B-E, from the thickest string (6th) to the thinnest (1st). The frequencies are: E2 (82.41 Hz), A2 (110.00 Hz), D3 (146.83 Hz), G3 (196.00 Hz), B3 (246.94 Hz), and E4 (329.63 Hz). This is the most widely used tuning for guitar and the default for most music.

Background noise makes pitch detection harder. Get the guitar's soundhole (or your phone's microphone) as close as practical, pluck the string firmly with your thumb over the pickups or soundhole, and let it ring cleanly — a single clear note reads better than strumming. If the display flickers between notes, mute the other five strings with your fretting hand so only one string sounds. Very quiet plucks may not register at all; the tuner ignores signals below a noise threshold on purpose.

No microphone? Press Play Reference Tone to hear the exact pitch of the selected string, then tune your string until the two sounds match. When you're close, you'll hear a slow "wobble" (beating) between your string and the tone — the wobble slows down as you get closer and disappears when you're in tune. Tuning by ear this way is also great ear training.

If every open string reads in tune but chords still sound sour, the usual suspects are old strings (worn strings ring out of tune with themselves), pressing too hard or behind large frets (which bends the note sharp), or intonation — the string length adjustment at the bridge that keeps fretted notes in tune higher up the neck. New strings also stretch: retune a fresh set several times in the first days. None of these are tuner problems, but the tuner can help you spot them: play the 12th-fret note and compare it with the open string.