How to Tune a Guitar by Ear: Relative & Harmonics

Tuning a guitar by ear is a feedback loop between your hands and two auditory skills: matching unisons and counting acoustic beats. It needs no batteries and it is the only way to hear intonation drift in a live room.

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1. How to Hear Acoustic Beats

When two notes of slightly different frequencies sound together, their waveforms alternately reinforce and cancel, producing a rhythmic swell in volume:

f(beat) = |f1 − f2|

If one string vibrates at 110.0 Hz and another at 112.5 Hz, you hear 2.5 pulses per second. As the flatter string approaches 110.0 Hz the pulses slow: 2 per second, then 1, then one every few seconds. When the motion stops and the two notes fuse into one steady tone, they are in unison.

Counting beats by ear:

• Above about 10 beats per second the pulses fuse into a rough buzz, so stop counting and turn the peg.
• Between 1 and 10 Hz, count the pulses over five seconds and divide by five (12 pulses in five seconds = 2.4 Hz).
• Below about 0.5 Hz, most players cannot time the pulses reliably. At A4 = 440 Hz, a 0.5 Hz beat is about 2 cents, a sensible place to stop and verify with a tuner.

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2. Step 1: Establish a Reference Pitch

Relative tuning can only be as accurate as the first string you anchor to an external pitch.

1. Open the Pitch Pipe and tap A (A4 = 440.00 Hz) or E (E4 = 329.63 Hz). The pipe covers C4 to C5 only, so it cannot sound the guitar’s low E2 = 82.41 Hz or A2 = 110.00 Hz directly.
2. Match the reference to a harmonic instead. The 5th-fret harmonic of the A string is its 4th harmonic: 4 × 110.00 = 440.00 Hz, exactly the pipe’s A. The 5th-fret harmonic of the low E string is 4 × 82.41 = 329.63 Hz, exactly the pipe’s E.
3. Touch the string lightly above the 5th fret wire, pluck it, and let it ring with the reference tone. Turn the peg until the beating stops, finishing from below pitch, and damp the other strings with your palm; a sympathetic ring adds a second beat frequency.

If your ensemble tunes to 442 Hz, the pipe’s fixed 440 Hz reference reads 7.85 cents flat; use the Guitar Tuner with its reference set to 442 instead.

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3. The 5th-Fret Relative Tuning Method

Standard tuning is mostly perfect fourths, so fretting a string at the 5th fret produces the pitch of the next open string:

Fret action	Produces	Match open string	Interval
Fret string 6 at the 5th fret	A2 = 110.00 Hz	String 5 (A)	Unison
Fret string 5 at the 5th fret	D3 = 146.83 Hz	String 4 (D)	Unison
Fret string 4 at the 5th fret	G3 = 196.00 Hz	String 3 (G)	Unison
Fret string 3 at the 4th fret	B3 = 246.94 Hz	String 2 (B)	Unison (major third)
Fret string 2 at the 5th fret	E4 = 329.63 Hz	String 1 (E)	Unison

The 4th-fret exception for the B string is the most common mistake here. Strings 3 and 2 are a major third apart (4 semitones, 400 cents), not a fourth, so the 5th fret of the G string gives C4, not B3.

Procedure:

1. Press the 6th string firmly behind the 5th fret and strike it.
2. Strike open string 5 while the fretted note is still ringing and listen for the beats.
3. Turn string 5’s peg until the pulses stop, approaching the pitch from below.
4. Repeat up the neck, using the 4th fret on string 3.
5. Check the result: the open A should still beat at zero against the pipe’s A, and each string’s 12th-fret harmonic should match its open pitch exactly.

Error accumulates in relative tuning. If the anchor string is 5 cents flat, every string derived from it is 5 cents flat too, so re-anchor every second string or verify at the end with a tuner.

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4. The 5th and 7th Fret Harmonic Method

Natural harmonics let both hands stay free to turn pegs while the strings ring, and they produce cleaner high partials than a plucked fundamental. A 12th-fret harmonic is the 2nd harmonic, exactly one octave up; the 7th fret gives the 3rd harmonic, an octave and a fifth up; the 5th fret gives the 4th harmonic, two octaves up.

The classic pairing is the 5th-fret harmonic on the lower string against the 7th-fret harmonic on the string above:

1. Touch above the 5th fret of string 6 (4 × 82.41 = 329.63 Hz) and the 7th fret of string 5 (3 × 110.00 = 330.00 Hz), and let both ring.
2. Turn string 5’s peg until the beating stops.
3. Repeat between strings 5 and 4, then 4 and 3.
4. Skip the 3–2 pair: the major third has no convenient shared harmonic, so use the 4th-fret method from section 3, then finish with the 5th-fret harmonic of string 2 against the 7th-fret harmonic of string 1.

Two arithmetic facts explain why harmonic tuning never quite agrees with a tuner. The 12th and 5th fret harmonics are exact octaves (2:1 and 4:1), so they are pitch-identical to equal temperament. The 7th-fret harmonic is the 3rd harmonic, 3:1, which is 1.96 cents sharp of the equal-tempered twelfth. Tune a fourth to zero beats and the lower string lands 1.96 cents flat; repeat at each string and the G finishes about 6 cents flat, with everything above inheriting the offset. Verify with an equal-tempered Guitar Tuner before recording or playing with fixed-pitch instruments.

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5. Troubleshooting and Common Mistakes

• Tuning in a loud room. A microphone hears the band, the PA and the cymbals. Use the harmonic method or a clip-on tuner.
• Tuning with a capo fitted. Capo pressure sharpens the strings; fit the capo first and tune with it in place.
• New strings stretch. Wound strings creep for the first hour and can drop 10 to 20 cents. Tune, play a few chords, retune.
• Stage heat. A guitar perfect at soundcheck is often 5 to 10 cents sharp after twenty minutes under lights; re-check the low E between songs.
• Phone tuners showing the wrong octave. If the app reports E3 for your low E, the fundamental is weak and the detector has locked onto a harmonic. Play the 12th-fret harmonic to confirm.
• Only checking one string. Play a full E major and a full B7 and listen for any string that beats against the rest.

For the mechanical side, see How to Tune a Guitar. The Ear Training drill sharpens the pitch discrimination that beat counting depends on.