Online Guitar Tuner

The tuner below is already set to guitar, so the six string targets are loaded and it will tell you which string you are nearest and how many cents you are away from it. Allow microphone access, play one string at a time, and read the needle. Nothing is recorded and nothing leaves your browser.

Everything runs in your browser. No audio is ever uploaded.

Standard tuning, string by string

Getting a clean reading from the microphone

A tuner is only as good as the signal it hears. Work in the quietest room available, sit close to the microphone, and mute anything else that makes sound, including a fan or an air conditioner: low frequency rumble confuses pitch detection on the bass strings more than you would expect. Laptop microphones are often mounted near the fan intake, which is worth knowing on a warm day.

Pluck once, firmly but not hard, and let the string ring. The first fraction of a second of a plucked note is full of overtones and inharmonicity, so give the reading a moment to settle and tune while the note is sustaining rather than immediately after the attack. If the display jumps between two notes an octave apart, you are plucking too hard and the fundamental is being swamped by the second harmonic.

Tuning order, and why the low E fights you

Work from the sixth string upward, then go back and check the sixth again. Every string you tighten adds tension to the neck, which pulls it forward a fraction and flattens the strings you already did, so one pass is never final on a guitar with fresh strings. Two or three passes is normal, and a new set will want retuning several times over its first days.

The low E is the hardest string for any tuner to read, including this one, because at 82 Hz the analysis window has fewer cycles to work with and the string's own inharmonicity is strongest. If the reading is unstable, fret the low E at the twelfth fret and tune that octave at 164.81 Hz instead, or play a harmonic there, which gives the detector a much cleaner tone to lock onto.

Alternate tunings by ear

This tuner has no preset for alternate tunings, so use the chromatic mode and tune each string to a named note yourself. Drop D lowers only the sixth string, from E2 to D2 at 73.42 Hz. Half a step down puts every string one semitone lower, so E2 becomes E flat at 77.78 Hz and the rest follow. Open G is D2, G2, D3, G3, B3, D4, which drops the sixth, fifth and first strings.

DADGAD is D2, A2, D3, G3, A3, D4, and it is the tuning most players reach for after drop D. In every case the fastest route is the same: switch the tuner to chromatic, play the string, and wait for the note name you want with the needle centred. Reference frequencies for any note you need are in the audio calculators.

When tuning is right but chords still sound wrong

Open strings in tune but barre chords sour higher up the neck is not a tuning problem, it is intonation. The saddle position for each string has to compensate for the extra tension that pressing the string to a fret adds, and if it is set wrong the fretted note at the twelfth fret will not match the harmonic at the same place. Compare those two with this tuner and you will see the error in cents.

Old strings do something similar. As a string wears unevenly it loses its harmonic regularity, which makes the tuner hesitate and makes chords sound slightly out no matter what the display says. If a string that was fine last month refuses to settle, change the set before you adjust anything on the guitar.

Where to go next

• Online Tuner: cents readout for guitar, bass, ukulele and violin
• Online Ukulele Tuner: the mic tuner preloaded with standard GCEA tuning
• Free Online Metronome: 20 to 300 BPM with subdivisions and tap tempo
• Online Tone Generator: one pure tone from 20 Hz to 20 kHz
• Spectrum Analyzer: live frequency bars and a scrolling spectrogram