Free Online Tuner for Guitar and 20+ Instruments

How a browser tuner works

You play a note. The microphone turns that sound into numbers, and the tuner works out the repeating rate of the waveform, its fundamental frequency, in Hertz. Then it compares that number against the twelve notes it knows, picks the closest, and reports how far off you are in cents: hundredths of a semitone, so 100 cents is one fret. Under about 5 cents, nobody can hear the difference. Over about 15, everybody can.

Everything happens on your own machine: the audio never needs to leave the browser, and a tuner that asks you to upload anything is doing something strange.

Getting a reading you can trust

1. Quiet room, one note at a time. A microphone hears everything. A fan, a backing track, someone else practicing: the tuner is trying to find one pitch in all of it, and it will sometimes pick the wrong one.
2. Play at a medium volume and wait. Hitting the string hard makes the note go sharp for the first moment and then settle. Tuners read the attack, wobble, then stabilise. The number after it settles is the true one.
3. Safety Tip about tuning. Turn tuning pegs slowly and deliberately. Turning too fast or tuning too far sharp puts sudden tension on the string, which can cause it to snap. While you can adjust pitch up or down, finishing by slowly bringing the pitch up into the target note gives you the best tuning stability. If you overshoot, detune slightly below the note and bring it up slowly.
4. Go round twice. Every string you tune changes the tension on the neck, which detunes the ones you already did. This is not the tuner being wrong.
5. For a stubborn low string, tune the harmonic. Touch the string lightly above the 12th fret and pluck. The tone is far purer than the open string, and the tuner will lock onto it immediately.

Why the low strings are the difficult ones

A low E on a guitar vibrates at about 82 Hz, and a bass low E at about 41 Hz. Three main factors make these notes tricky for a tuner to read. First, low strings, especially on unamplified electrics or basses,produce less acoustic volume, making the physical sound harder for your microphone to pick up cleanly. Second, measuring low frequencies takes time; at 41 Hz, each cycle lasts 24 milliseconds, so the tuner needs more time to observe enough full cycles to confirm the pitch. Finally, low strings produce strong overtones that are often louder than the fundamental frequency itself, which is why a tuner might confidently misread your low E as an E an octave up.

This is why a tuner that seems flaky on the bottom two strings is usually fine on the top four. Harmonics fix it. So does simply giving it a moment.

When the tuner is right and the chord is still wrong

This is the frustrating one, and it means the problem is not tuning. Three usual suspects:

• Intonation. Check an open string against the note at the 12th fret. They should be the same note an octave apart. If the fretted note is sharp, the string is effectively too short and the bridge saddle needs to move back. No amount of tuning the open string will fix a fretted note.
• Your fretting hand. Pressing hard behind the fret stretches the string and pulls the pitch up, worst in the first three frets and on light strings. If your chords go sharp but your open strings are fine, this is it.
• Equal temperament. Frets divide the octave into twelve equal steps so that every key works, and the price is that the major third sits about 14 cents sharper than the pure interval your ear wants. A big open major chord will always sound slightly hard. This is not fixable, only understandable.

A drone is the fastest way to work out which of the three you have: hold the chord over a drone on its root and listen for which string causes the churn. There is a full method in Practicing with a drone.

Alternate tunings, and knowing what to aim at

A chromatic tuner tells you what note you are playing. It cannot tell you what note youshould be playing. That is on you, and it is where most alternate-tuning attempts go wrong. Drop D, DADGAD, open G, and the standard tunings for twenty-odd other instruments all live in the tuning reference, with the note, octave and exact frequency for every string, plus a piano you can sound any note from if you would rather tune by ear.

If you are matching a recording rather than a standard, check the pitch of the recording first. Plenty of records sit a little sharp or flat of 440. Retuning your whole instrument to chase one is a lot of work when shifting the recording instead takes a second.

Tune first, then everything else

It takes twenty seconds and it removes an entire category of problem from the rest of the session. Practicing on an out-of-tune instrument trains your ear toward the wrong target, which is worse than not practicing the passage at all. Tune, then put the metronome on.