How to use the guitar tuner
This guitar tuner online works straight from your browser, with no app to install. Press Allow microphone when your browser asks for access. Then play one open string and let it ring. The display shows the note name with its octave, such as A2, and a needle that leans left when the string is flat and right when it is sharp.
Turn the tuning peg slowly while the note sustains. Tighten to raise the pitch, loosen to lower it. When the needle stays within five cents of center, the tuner marks the string as in tune. Move on to the next string and repeat. For a regular six-string guitar, the targets from low to high are E2, A2, D3, G3, B3 and E4, and that list stays visible on the page so you never have to remember it.
How pitch detection works
A vibrating string repeats the same wave shape many times per second. The tuner takes short slices of audio from your microphone and compares each slice with delayed copies of itself, a method called autocorrelation. The delay at which the signal lines up best with itself is the length of one cycle, and from that the tool calculates the frequency in hertz. It searches between 50 and 1200 Hz, which spans the useful range of a guitar.
That frequency is then mapped onto the twelve-tone scale using A4 = 440 Hz as the reference. The nearest note becomes the label, and the leftover distance is expressed in cents. One semitone equals 100 cents, so the needle covers half a semitone in each direction, from −50 to +50.
Tips for a faster, steadier tune
- Find a quiet room. Fans, TV and conversation confuse the reading.
- Pluck only one string at a time and mute the others with your palm.
- Play with a medium attack. A very hard pluck pushes the pitch sharp for a moment; read the needle once the note settles.
- Always tune up to the note. If you overshoot, drop below the target and come back up so the string holds better.
- Check every string twice. Changing one string’s tension slightly shifts the neck, especially on guitars with fresh strings.
If a reading jumps between neighboring notes, move the phone or laptop closer to the sound hole and try again.