Online Guitar Tuner

Pluck a string and the tuner listens through your microphone: it names the note and shows how far flat or sharp it is, for standard tuning (E2 A2 D3 G3 B3 E4) or 13 other tunings such as Drop D and DADGAD.

Tuner

A4 · 440 Hz
-50-250+25+50♭♯FLATSHARP
–
Mic off
±0 ¢
Auto string detect

Uses your microphone. Audio stays on this device. No mic? Tap a string to hear its note.

Strings · tap to hear

Standard tuning notes and frequencies

  • String 6 (thickest): E2 · 82.41 Hz
  • String 5: A2 · 110.00 Hz
  • String 4: D3 · 146.83 Hz
  • String 3: G3 · 196.00 Hz
  • String 2: B3 · 246.94 Hz
  • String 1 (thinnest): E4 · 329.63 Hz

Standard tuning guide

The number after the letter is the octave: E2 and E4 are both E, two octaves apart, so the thinnest string vibrates four times as fast as the thickest. Frequencies follow the A4 setting above (440 Hz by default).

Tuned up? Play your first chords

How to tune an acoustic guitar, step by step

  1. Press Start tuner and allow the microphone. Put the phone within 50 cm of the soundhole.
  2. Pluck one string and let it ring. The big letter is the note that string should be; the line under it names the string and its frequency.
  3. Needle left and the word Flat: tighten the string. Right and Sharp: loosen it. Stop when it reads In tune (within 5 cents). The string button gets a tick.
  4. Go through all six strings, then check them once more: changing one string's tension pulls the others slightly.
  5. In a noisy room, tap a string button to lock the tuner to that string. Tap Auto detect to go back.

Which way to turn the peg: turning it so more string winds onto the post tightens the string and raises the pitch. On a 3+3 headstock the strings wind on from the centre side of each post, so the bass-side and treble-side pegs turn in mirror image. Not sure? Turn a quarter turn and watch the needle: moving right means the string went up.

Tune up to the note where you can: a string that comes up to pitch holds better than one pushed past it and let down.

Tune by ear: the fifth-fret method

No tuner at all? Get string 6 right first (tap its button above, or use any piano or app), then tune each string to the one below it:

  1. Fret string 6 at fret 5: that is A2. Tune open string 5 until it sounds the same.
  2. Fret string 5 at fret 5: that is D3. Tune open string 4 until it sounds the same.
  3. Fret string 4 at fret 5: that is G3. Tune open string 3 until it sounds the same.
  4. Fret string 3 at fret 4: that is B3. Tune open string 2 until it sounds the same.
  5. Fret string 2 at fret 5: that is E4. Tune open string 1 until it sounds the same.

String 3 uses fret 4, not 5, because G to B is a major third, one fret shorter than the other gaps. The method keeps the strings in tune with each other; only the first string decides whether the guitar matches other instruments.

How a guitar tuner works

The microphone delivers a stream of samples, usually 44,100 or 48,000 per second. About 30 times a second this tuner takes the latest 2,048 samples (around 43 ms of sound) and finds the delay after which the waveform repeats itself. That delay is one period of the string's fundamental; one divided by the period is the frequency in hertz. The method is a refined autocorrelation (McLeod's normalised square difference), and the last five readings are smoothed with a median so one bad frame cannot flick the needle.

The frequency is then compared with the nearest string of the tuning you picked. The gap is shown in cents: 100 cents is one semitone (one fret), and cents = 1200 × log₂(your frequency ÷ target). The needle covers ±50 cents, half a fret either way; within ±5 cents the tuner shows In tune.

Clip-on tuners do the same maths but read vibration through the headstock, so room noise does not reach them. A microphone tuner hears the room, which is why it works best close to the soundhole with one string ringing at a time.

Why your acoustic guitar keeps going out of tune

  • New strings are still stretching. For the first days they keep going flat. After fitting, pull each string gently away from the fretboard along its length, retune, and repeat two or three times.
  • Temperature and humidity changed. Wood and steel both move with the room. A guitar brought in from a cold car drifts as it warms up; let it reach room temperature, then tune.
  • You tuned down to the note. Slack left in the gear or at the nut lets the string slip flat later. If a string is sharp, go below the note and come back up to it.
  • The string slips at the post or the bridge. Too few wraps on the tuning post, or a bridge pin that is not seated, lets the string creep. Push the pin in and pull the string up so the ball end sits against the bridge plate.
  • The string sticks in the nut. If you hear a small ping while tuning and the pitch jumps, the slot is binding. Rubbing soft pencil graphite into the slot usually cures it.
  • You press too hard, or the capo does. Squeezing a fret or clamping a capo too tight bends strings sharp. Retune with the capo on.
  • Open strings are right but chords up the neck are not. That is intonation, set at the saddle, not tuning. A setup by a repair shop fixes it.

Tunings in this tuner

TuningStrings 6 → 1Open strings soundChanged from standard
Standard E A D G B E not a chord –
Drop D D A D G B E not a chord 1 of 6
Half step down E♭ A♭ D♭ G♭ B♭ E♭ not a chord 6 of 6
Open D D A D F♯ A D D chord 4 of 6
DADFAD (open D minor) D A D F A D Dm chord 4 of 6
DADGAD D A D G A D Dsus4 chord 3 of 6
Open G D G D G B D G chord 3 of 6
Open E E B E G♯ B E E chord 3 of 6
Open C C G C G C E C chord 4 of 6
Drop C C G C F A D not a chord 6 of 6
Open A E A E A C♯ E A chord 3 of 6
Drop B B F♯ B E G♯ C♯ not a chord 6 of 6
Open F F A C F C F F chord 5 of 6
Drop A A E A D F♯ B not a chord 6 of 6

Pick any of them in the Tuning menu above; the string buttons and the retune steps follow. All guitar tunings groups them by type, with chord shapes for each.

FAQ

What are the notes of standard guitar tuning?

From the thickest string (6) to the thinnest (1): E2 A2 D3 G3 B3 E4. The A string is 110 Hz when A4 is 440 Hz.

Is the microphone audio sent anywhere?

No. Pitch detection runs in your browser on your device. Nothing is recorded or uploaded, and the microphone is released when you press Stop or leave the tab.

Should I use A4 = 440 or 432 Hz?

Use 440 Hz, the modern standard, unless you play along with a recording or a group tuned differently. 432 Hz puts every string about 32 cents lower.

Why does the needle jump around?

The first moment of a pluck is noisy and the tuner may hear an overtone. Pluck one string once, let it ring, and read the needle after a second. In a noisy room, tap the string button to lock the tuner to that string.

Can I tune without a microphone?

Yes. Tap a string button to hear its reference note, then turn the peg until your string and the tone sound the same and the slow wobble (beating) between them stops.

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