Guitar Tuner

What this tool does

This guitar tuner listens to your instrument through your device’s microphone and tells you, in real time, whether each string is in tune. Pluck a string and the tool detects its pitch, shows the nearest musical note, and displays a tuning meter with a needle that sits left of centre when the string is flat and right of centre when it is sharp. A cents read-out gives the precise amount, so you can dial each string in exactly.

Under the hood it uses a hand-rolled autocorrelation pitch-detection algorithm — the same family of technique used by professional tuning software. It looks for the repeating period in the incoming waveform, converts that to a frequency, and matches the frequency to the closest note in equal temperament. All of this runs in your browser; the tuner needs nothing but a microphone and a quiet moment.

When you would use it

Any time your guitar sounds slightly off. Strings drift out of tune with temperature changes, with playing, and simply with time, so a quick check before you practise or perform is routine for every guitarist. Beginners use a tuner constantly while their ear is still developing, and even seasoned players keep one handy because no ear is perfect against a fixed reference. It is also useful after changing a string, which always needs several rounds of tuning as the new string stretches and settles. Because the display reports any pitch, the same tool helps when tuning a bass, ukulele, mandolin or violin by ear.

How to use it

1. Click Enable microphone and allow microphone access when your browser asks.
2. Choose a string to tune. Leave the picker on auto-detect to tune by ear, or select a specific string (6 to 1) to lock the meter onto that target.
3. Pluck one string firmly near the middle of its length and let it ring.
4. Read the note name and watch the meter. The needle shows flat to the left, sharp to the right, in tune in the centre green band.
5. Turn the tuning peg: tighten the string if it reads flat, loosen it if it reads sharp, until the needle settles in the centre.
6. Repeat for each string. When finished, press Stop to release the microphone.

How to read the result

Standard tuning is E A D G B E, from the thick sixth string to the thin first. A correct read for the sixth string is E; for the first string, also E but two octaves higher. The cents number is the fine detail: zero is perfect, and you are comfortably in tune within five cents either side. Tune slightly below the target and then up to it — bringing a string up to pitch holds better than easing it down. The clarity percentage indicates how clean the detected signal is; if it is low, mute the other strings and pluck again in a quieter spot.

After tuning, keep your timing honest with the metronome or the drum practice click. To look up the exact target frequency for any string or note, see the note frequency reference, and to explore which notes belong together, try the piano scale reference. If you are working with a recording, the audio trimmer edits clips in the browser, and the Pomodoro timer keeps practice sessions on track.

Privacy

Your microphone audio is analysed entirely inside your browser. Each fraction of a second of sound is run through the pitch detector and immediately discarded — nothing is recorded, nothing is saved, and no audio or result is ever uploaded to a server. The tool requests microphone access only so it can hear the string you play, and it releases that access the instant you press Stop or leave the page. You stay in full control, and you can withdraw the permission whenever you like through your browser’s site settings.