Online guitar tuner (free, microphone)

How to use the tuner

1. Enable the microphone with the button, then grant the permission the browser asks for. The page must be on HTTPS, which is the case on this site.
2. Pick a tuning from the list: standard, drop D, drop C, half a step or a whole step down, DADGAD, open G, open D, open E, 7-string guitar, 4- or 5-string bass.
3. Play an open string. The needle shows how far you are from the nearest note, in cents (a semitone is 100 cents). The note name and the frequency in hertz appear below.
4. Turn the tuning peg until the needle enters the centre zone, within plus or minus 3 cents. Too far left, the string is flat: tighten it. Too far right, it is sharp: loosen it.
5. By default the tool detects the closest string automatically. If it gets confused on the low strings, lock the target string by clicking on it.

The reference tones let you tune by ear: play the tone for a string, then the string itself, and make the beating disappear. The pitch reference can be set from 415 to 466 Hz, with shortcuts for 432, 440 and 442 Hz. Leave it at 440 Hz unless you have a specific reason to change it.

Guitarist’s tips

• Always tune up to the note. If the string is sharp, drop it clearly below pitch, then bring it back up. The string then seats against the nut and the peg in the direction of tension and holds its tuning longer.
• Mute the strings you are not tuning with the edge of your palm. A neighbouring string ringing in sympathy confuses the detection and makes the needle shake.
• Play more softly than you think. A hard attack pushes the pitch up for a fraction of a second. A medium attack, read after about a second, gives the true value.
• Check intonation at the 12th fret. Once the open string is in tune, compare the natural harmonic at the 12th fret with the note fretted at the 12th fret. If the fretted note is sharp, the saddle needs to move back; if flat, forward. The guitar care guide covers the procedure.
• After a string change, gently stretch each string, retune, and repeat two or three times. New strings that will not hold their tuning have simply not finished stretching.

Limits and transparency

This tuner analyses the signal from your device’s microphone. Its accuracy therefore depends on that microphone and on background noise: in a quiet room with a recent laptop, the reading is stable to within a cent; in a rehearsal room or with a cheap microphone, it becomes erratic, especially on the low E and on bass.

It does not replace a clip-on tuner, which reads the vibration of the wood and ignores noise, or a tuner pedal, which mutes the signal and reads the guitar’s output directly. In a band, at rehearsal and on stage, one or the other remains essential. Our guitar tuner comparison and the TC Electronic PolyTune 3 review show what you gain by spending the money.

Finally, the tool does not do polyphonic tuning: it reads one string at a time. Strum all six strings together and it will return a mess of notes.

Going further

• The online metronome to practise what you have just tuned in time.
• The string tension calculator if you drop to C or move to an open tuning: a suitable gauge holds its tuning better.
• The essential accessories for beginners, including a physical tuner to carry everywhere.