Guitar Tuner

A tuner that listens to the string you actually play

Most guitars drift a little every day. Strings stretch, a warm room expands the neck, a bend on the high E pulls the whole set sharp. This page gives you a quick way to check all six strings before you start playing, using nothing but the microphone already in your laptop or phone.

The readout has three parts. A needle swings left when the string is flat and right when it is sharp. Below it you see the note the tuner thinks you are aiming for. Under that, a short instruction says tune up or tune down. When the string lands within three cents of the target, which is three hundredths of a semitone, the display switches to In tune. Three cents is far smaller than a difference most people can pick out in a band mix, so you are not chasing an impossible number.

The string buttons work the other way around. Press the one marked A and the page plays a reference tone for A2, which gives you something to match by ear if you prefer to hear the target rather than read it. Tuning by ear and tuning by needle complement each other, and the buttons let you switch between them without leaving the page.

Pitch detection here follows a YIN-style method: the page looks for the repeat length of the waveform coming from the microphone and converts it to a frequency. That approach copes well with the thick, harmonic-rich sound of a plucked string, where a simple loudest-peak method would often jump to an overtone and show you a note an octave or a fifth too high.

String order and how to turn the pegs

In standard tuning the six strings run, from the thickest to the thinnest, E A D G B E. The thickest is called the sixth string and sits nearest your face when you hold the guitar to play. A common memory aid is Eddie Ate Dynamite, Good Bye Eddie. The first and last strings share a letter name but sit two octaves apart, which is why the low E is called low and the thin one high.

Tuning pegs are geared, so a small turn makes a small change. Which direction raises the pitch depends on how the string wraps the post and which side of the headstock the peg sits on, so do not rely on a rule you half remember. Make a tiny move, watch the needle, and if it travels the wrong way, reverse.

Always approach the note from below. If the needle shows sharp, drop the string a little under the target, then bring it up to pitch. A string tuned downward tends to creep flat as it settles in the nut slot and around the tuner post. Coming up to the note leaves tension on the winding where it will stay put. Pluck with a moderate stroke each time, because hitting hard pushes the pitch sharp for the first half second and the needle will exaggerate.

Tune in whatever order feels natural, then go around once more. Changing the tension on one string slightly bends the neck and nudges the others, so the first string you tuned will often be a few cents off by the time you reach the sixth. A second pass with the needle takes thirty seconds and is worth it.

The tunings on offer

The list contains Standard, Drop D, Half step down, Whole step down, Drop C, DADGAD, Open G, Open D and Open E, plus two bass layouts. Each one changes the target notes behind the buttons, and the table in the Numbers tab lists the frequencies for the main ones so you can see exactly what the tuner is comparing against.

Drop D lowers only the sixth string by a whole step, from E to D, which makes the bottom three strings a power chord under one finger. Half step down and whole step down lower the entire guitar by one or two semitones. Players choose them to ease the strain on a singing voice, to make bends feel lighter, or because a record they are learning was cut that way. Drop C does the Drop D move and lowers the whole instrument by another whole step, so use a heavier string gauge if the strings flap against the frets.

DADGAD swaps three strings to make an open, suspended sound that rings without fretting anything. Open G, Open D and Open E arrange the strings into a full chord when strummed open, which is the basis of slide playing: lay a finger or a slide across any fret and you have a major chord. Tune toward an open chord a step at a time and check the strings you leave alone, because pulling the third and fourth strings up or down shifts the neck angle.

The page remembers the tuning you picked last. Open it a week later and the same list entry is waiting, which saves a tap if you play in one alternate tuning most of the time.

Capo and intonation: when a tuned guitar still sounds wrong

A frequent complaint is that the guitar was in tune a minute ago but sounds sour with the capo on. A capo clamps the strings against a fret, and if it presses too hard it bends the strings sharp, more on some strings than others. Tune first with the capo off, clamp it just behind the fret with the lightest pressure that stops buzz, then check each string again. Many capos also move the string over the fret slightly, so expect a couple of cents of drift and trust your ears for the last touch.

If the open strings read In tune but chords up the neck sound off, the problem is intonation, not tuning. Intonation means that the note at the twelfth fret should be exactly one octave above the open string. Play the open string with the tuner, then play the harmonic at the twelfth fret and then the fretted note at the same fret. If the fretted note reads sharp compared with the harmonic, the saddle needs to move back toward the tail. If it reads flat, move it forward. A luthier does this in minutes, and a tuner like this one is how they check.

New strings also lie. Fresh strings stretch for the first day or two and fall flat repeatedly. Pull each string gently away from the fretboard along its length a few times, retune, and repeat until the needle stops moving. Old strings lose their clear overtones, so the needle will wobble around the target even though your tuning is correct.

Low E, quiet rooms and bass mode

The sixth string at E2 vibrates about 82 times per second. That is a slow wave, and a tiny phone microphone needs a few cycles to measure it, so the readout may take a beat longer on the low E than on the high strings. Play it firmly, let it sustain, and keep the guitar close to the device. If the open string still looks jumpy, check that nothing else in the room is making a steady sound.

Background sound confuses any tuner that listens through a microphone. A television, a fan, or a friend singing along make the needle jump because the detector picks the strongest repeating pitch it hears. Mute the room or hold the guitar near the microphone. An unplugged electric guitar is quiet, so move closer than you would with an acoustic, or turn up a small amp and tune with the amp next to the device.

Choose Bass, 4-string for the targets E1 A1 D2 G2, or Bass, 5-string to add the low B at about 31 Hz. These are close to the floor of what a phone microphone can follow, so pluck firmly, let the note sustain and hold the instrument close to the microphone. The bass options use the same needle and the same three-cent window.

Reference pitch: 440, 442 and 432

The reference setting sets the frequency assigned to A4, the A above middle C. The default is 440 Hz, the modern standard. A setting of 442 Hz is used by some European orchestras, and 432 Hz appeals to people who like the sound of a slightly lower reference. For a guitar playing with a piano, keyboard or backing track, match what they use. If you play alone, any consistent reference works, and the guitar will sound the same relative to itself.

Changing the reference moves every string by the same ratio. At 432 Hz all notes sit about 32 cents lower than at 440, which is roughly a third of a semitone. It is perceptible when you play along with a recording, so do not switch it casually if you are jamming with a track.

Tuning without a tuner, and when you need one

Players have tuned by ear for centuries. The classic method is to match the fifth fret on the sixth string to the open fifth string, then continue through the strings, using the fourth fret instead of the fifth when you reach the second string. It works well if the first string is right, but any error accumulates across the set, so the sixth string and first string may disagree a little by the end.

That is where a microphone tuner earns its place. Tune the low E by the needle, use the ear method for the remaining strings, then check them against the buttons. You get the speed of ear tuning with the accuracy of a reference. Whatever method you use, finish by strumming an open chord such as G or D. If a chord sounds shimmery or sour in a way a single note did not, one string is still a few cents off.

Privacy and the microphone

The browser asks permission before the page can hear anything. Sound is analyzed as it arrives, turned into a pitch value and discarded, so there is no recording to find later and no audio travels to a server. Close the tab and the microphone is released. On a phone the browser shows its usual indicator while the tuner runs, which is a handy way to confirm it has stopped.