How to use the guitar tuner
- Choose your tuning. Standard E A D G B E is the default; drop D, half step down (E♭), DADGAD, open G, open D, 4-string bass, ukulele and violin are in the list.
- Press Start tuner and allow the microphone when the browser asks. Hold your phone or laptop close to the guitar — near the sound hole of an acoustic, or near the amp of an electric.
- Pluck one string firmly and let it ring. The big letter is the string the tuner thinks you are tuning, the bar shows how far off you are, and the line below gives the exact frequency and the nearest note.
- If it says Too low — tune up, tighten the string; Too high — tune down, loosen it. Turn the peg in small steps and pluck again. Within ±5 cents the bar and the string button turn green: that string is in tune.
- Repeat for every string, then check them all once more: tightening one string nudges the others.
No microphone, or a noisy room? Tap a string button to hear its reference tone and tune by ear until the two notes stop “beating” (the slow wobble you hear when two pitches are almost the same). If the tuner hears nothing, run the microphone test first.
Everything happens in your browser: the sound from the microphone is analyzed on your device and is never recorded, stored or uploaded.
How the tuner finds the note
A plucked string repeats the same wave shape over and over; the repeats per second are its frequency in hertz (Hz). About 16 times a second the tuner compares the last tenth of a second of sound with copies of itself shifted in time. The shift at which a copy lines up best is one period of the wave, and the frequency is 1 ÷ period (the McLeod pitch method, a normalized autocorrelation). Unclear moments — silence, speech, two strings at once — are ignored, and the display shows the median of the last few readings so the bar doesn’t flicker.
The offset is shown in cents: 100 cents make one semitone (one fret) and 1,200 make an octave. Cents = 1,200 × log₂(measured ÷ target). For example, an A string at 111 Hz instead of 110 Hz is 1,200 × log₂(111 ÷ 110) ≈ +16 cents — sharp by about a sixth of a fret. Differences of a few cents are hard to hear on a single note, which is why ±5 cents counts as in tune here.
String frequencies for every tuning
Target frequencies at A4 = 440 Hz, from the lowest string to the highest, in equal temperament (each fret multiplies the frequency by the twelfth root of 2):
| Tuning | Strings (Hz) |
|---|---|
| Guitar — standard (E A D G B E) | E2 82.41 · A2 110.00 · D3 146.83 · G3 196.00 · B3 246.94 · E4 329.63 |
| Guitar — drop D (D A D G B E) | D2 73.42 · A2 110.00 · D3 146.83 · G3 196.00 · B3 246.94 · E4 329.63 |
| Guitar — half step down (E♭ A♭ D♭ G♭ B♭ E♭) | E♭2 77.78 · A♭2 103.83 · D♭3 138.59 · G♭3 185.00 · B♭3 233.08 · E♭4 311.13 |
| Guitar — DADGAD | D2 73.42 · A2 110.00 · D3 146.83 · G3 196.00 · A3 220.00 · D4 293.66 |
| Guitar — open G (D G D G B D) | D2 73.42 · G2 98.00 · D3 146.83 · G3 196.00 · B3 246.94 · D4 293.66 |
| Guitar — open D (D A D F♯ A D) | D2 73.42 · A2 110.00 · D3 146.83 · F♯3 185.00 · A3 220.00 · D4 293.66 |
| Bass — 4-string (E A D G) | E1 41.20 · A1 55.00 · D2 73.42 · G2 98.00 |
| Ukulele — standard (G C E A) | G4 392.00 · C4 261.63 · E4 329.63 · A4 440.00 |
| Violin (G D A E) | G3 196.00 · D4 293.66 · A4 440.00 · E5 659.26 |
The international standard pitch, ISO 16, sets the A above middle C at 440 Hz. Some bands and orchestras tune slightly higher or lower; set Reference pitch A4 to match a piano or a recording, and every target moves with it:
| A4 | Low E (E2) | A (A2) | High E (E4) |
|---|---|---|---|
| 432 Hz | 80.91 Hz | 108.00 Hz | 323.63 Hz |
| 440 Hz | 82.41 Hz | 110.00 Hz | 329.63 Hz |
| 442 Hz | 82.78 Hz | 110.50 Hz | 331.13 Hz |
| 444 Hz | 83.16 Hz | 111.00 Hz | 332.62 Hz |
Tips for a guitar that stays in tune
- Tune up to the note. If a string is sharp, loosen it below the target and then bring it up. The string settles against the nut and the tuning gear holds it, so it is less likely to slip flat while you play.
- Read the note after the attack. A hard pluck is briefly sharp; watch the bar once the note settles, about half a second later.
- New strings stretch. Expect to retune several times during the first day. Changes in temperature and humidity also pull a guitar out of tune.
- Check the intonation. Tune the open string, then play the same string at the 12th fret: it should read the same note one octave higher. If the fretted note is sharp or flat by more than a few cents, the saddle needs adjusting — a job for a guitar tech if you have never done it.
- Then practice in time with the online metronome.
Frequently asked questions
Is my audio recorded or uploaded?
No. The tuner analyzes the microphone signal inside your browser, a tenth of a second at a time, and keeps nothing. No sound leaves your device, and the microphone stops as soon as you press Stop tuner or leave the page.
Why does the tuner show the wrong string?
It picks the string of your tuning closest to the note it hears. A string that is far out of tune — more than half the distance to the next string — can be shown as its neighbor. Bring it roughly into range by ear, or with the reference tones, and the right string lights up.
Can I tune a bass, ukulele or violin?
Yes. Choose Bass — 4-string (E1 A1 D2 G2), Ukulele — standard (G4 C4 E4 A4, the re-entrant tuning where the G string is high) or Violin (G3 D4 A4 E5). The nearest-note line works as a chromatic tuner for any other instrument.
Why doesn’t it react to my low E string?
Phone and laptop microphones pick up very low notes weakly. The tuner also uses the string’s overtones, so it usually still works: pluck firmly, hold the microphone close and keep the room quiet. If the light stays off, check your microphone with the mic test.
Last updated: October 15, 2026