12 string guitar tuner: every pair, with your mic

This is a free online tuner for 12 string guitar. It opens on standard tuning, E A D G B E, which is how the six main strings of a 12 string are tuned. The reading is chromatic, so it also reads the octave strings, as long as you follow one rule, explained below: tap the button of the pair you are tuning first. No account, no download. It sits alongside the rest of our free guitar tools.

12 string tuning: the notes of each pair

A 12 string is tuned like a six string, E A D G B E, but every note is doubled. The strings come in six pairs, called courses. In standard tuning, the four low courses are in octaves: next to each main string sits a thinner one, an octave higher. The two high courses, B and E, are in unison: both strings play the same note.

Frequencies are at A 440, the default reference pitch of the tuner.

How to tune a 12 string, string by string

There is no 12 string preset, and you do not need one. Tune the six main strings like a six string guitar, then bring each twin onto its partner.

1. Press Start and allow the microphone. Play one string at a time, and mute the other string of the pair with a finger, otherwise the tuner hesitates between the two.
2. Open Settings, below the tuning menu, and tick Open string sound: the six string buttons appear. Tapping one also plays its reference tone, so let it fade before you play.
3. Tune the main string of each course, the thicker one, exactly as on a six string: E2, A2, D3, G3, B3, E4. Start from the low E and work toward the high strings.
4. For each octave string, tap the button of its course first: E, A, D or G. Then play the thin string on its own. The large letter shows its note, E, A, D or G, and the cents show how far off it is.
5. For the two unison courses, B and E, tune the second string to the same note as the first, with its button selected.
6. Stretch each pair very gently, then go round once more, string by string.
7. Check with an open chord, E minor or G, and a slow arpeggio against the online metronome.

Standard pitch, or a half step down?

This is the real debate among 12 string owners. Twelve strings put almost twice the tension of a six string on the neck. Hence a very common habit, especially on older or entry level instruments: tune the whole guitar a half step down, to Eb, and put a capo on the first fret to get back to standard keys.

• Less tension: the neck and the top work less, and the instrument ages better.
• Easier to play: barre chords on a 12 string tire you quickly, and a half step less is felt at once under the fingers.
• Nothing lost musically: with the capo on the first fret, you play the same positions as everyone else.

A well built modern 12 string holds standard pitch without trouble on a light set. But if yours is old, the action is creeping up, or playing it wears you out, Eb plus a capo is the tried and tested answer. To tune it, pick Eb standard in the menu, or open the half step down tuner, and use the same method: the course button first, then the twin string.

Keeping a 12 string in tune

• Gentle stretch: pull each pair lightly, play it again, retune.
• Nut and bridge: if a string catches, a luthier can polish the slots.
• Humidity: aim for 45 to 55% relative humidity, and keep the guitar in a hard case.
• Capo: check the tuning again after putting the capo on.
• Intonation: if it is in tune open but out at the twelfth fret, have the intonation set. The other reasons a guitar in tune still sounds wrong are worth a look too.

Songs where the 12 string is easy to hear: All Along the Watchtower, Wish You Were Here, Hotel California, Stairway to Heaven, Wanted Dead or Alive, Space Oddity. The unison of the high courses and the octaves in the low ones are what give them that shimmer, and they are also what shows first when one string has drifted.