Why your guitar keeps going out of tune, even on its own

If your guitar goes out of tune by itself while it sits on the stand, or so fast it won’t last a single song, the cause is almost always one of these: new strings that are still stretching, changes in temperature and humidity, or a part with some play in it (the tuning pegs, the nut, the bridge or the tremolo).

It isn’t a defect: wood and metal move with their surroundings. With well-stretched strings, tuners in good shape and a nut that doesn’t bind, a stable guitar stays in tune for most of a rehearsal. Here is each cause and what to do about it.

1. New strings that are still stretching

This is by far the most common reason behind “I just tuned it and it’s already flat”, and why a new or freshly restrung guitar drifts out of tune so quickly. A new string has to settle in: over its first hours of playing it stretches and goes flat again and again. Nothing is broken; that is simply what metal does under tension.

What to do: after fitting new strings, gently pull each one up and away from the fretboard at a few points along the neck, retune, and repeat a few times. Nylon strings on a classical guitar take much longer to settle, sometimes days, because nylon is far more elastic than steel.

2. Temperature and humidity

This is what makes a guitar go out of tune on its own, sitting in its case untouched. A guitar is mostly wood, and wood swells and shrinks with the humidity in the air, while steel strings change tension with temperature. Carrying it from a heated room into the cold outside, or playing in the sun or next to a radiator, will pull it out of tune within minutes. Big, sudden changes are the worst.

What to do: when the guitar has come from somewhere very cold or very hot, let it acclimatise before you play. Keep it in its case and, in dry climates, consider a case humidifier. Don’t leave it in direct sun or right next to a heat source.

3. Tuning pegs

Worn, poorly lubricated or loose tuning machines don’t hold the tension properly, and the string slowly slips. How you wound the string matters too: too few wraps, or wraps piled up unevenly, let the string give.

What to do: wind the string with several neat wraps running down the post. If one particular tuning machine won’t hold pitch however much you adjust it, it may need tightening or replacing.

4. The nut

The nut is the slotted piece next to the headstock that the strings pass over. If a slot is too tight or has a burr, the string catches as you tune: you bring it up to pitch, but the extra tension stays trapped at the nut and lets go suddenly when you play, leaving you out of tune. It is a classic reason why one string, often the G or the B, is always the one that drifts.

What to do: a little lubricant in the slots stops the binding; there are products made for it, and pencil graphite works too. If the problem persists, a guitar tech can dress the slots.

5. The tremolo

If your electric has a whammy bar, especially with a floating bridge, it is a usual suspect. A floating bridge sits balanced between the pull of the strings and the springs in the back of the body. When you use the bar, the strings slide through the nut and the string trees on the headstock, and friction can stop them returning exactly to where they were: after a deep dive or heavy vibrato, one or more strings end up a little sharp or flat.

The same balance explains another oddity: tuning one string moves the others, because the bridge gives a little one way or the other. And when you bend one string, the others go slightly flat.

Tune in several passes: go through every string, start again, and repeat until none of them move.
Lubricate the nut and the string trees on the headstock, which is where the string usually catches.
Stretch new strings thoroughly before you use the bar hard.
If you hardly ever use the tremolo, you can deck the bridge against the body or block it; the guitar becomes much more stable. Floyd Rose-style bridges, with a locking nut and fine tuners, are designed precisely to hold tuning under heavy whammy use.

6. Technique: bends, capo and a heavy hand

Pressing the strings too hard against the frets, bending aggressively or putting the capo on crooked all pull the tuning. Pressing harder than you need to raises the pitch of every note slightly, which can sound out of tune even when the open strings are spot on.

What to do: press just hard enough for the note to ring cleanly, put the capo on straight and just behind the fret, and check your tuning after a session full of bends.

7. Out-of-tune octaves (intonation)

If the open strings are in tune but chords sound worse the further up the neck you go, the problem may not be tuning at all but intonation: the string’s effective length is not set right, so the 12th fret doesn’t give an exact octave. This is adjusted at the bridge, not at the tuning pegs.

What to do: compare the 12th-fret harmonic with the fretted note at the 12th fret on the same string. If the fretted note is sharp, the string needs lengthening at the bridge; if it is flat, shortening. On electric guitars this is done with the saddle screws; on acoustics it is a job for a tech.

How to keep your guitar in tune for longer

A few habits prevent most of these problems:

Stretch new strings thoroughly before a gig or a recording.
Always tune up to the note: reach the pitch by tightening, not loosening, so the tuning peg stays under steady tension.
Lubricate the nut if one particular string resists as you tune.
Let the instrument acclimatise and avoid sudden changes in temperature.
Check your tuning often: going through every string with the tuner takes a few seconds.

Frequently asked questions

Why does my new guitar go out of tune so fast?

Because its strings are still stretching. A new string goes flat again and again during its first hours of playing. Stretch them by gently pulling on each one, and retune a few times until they settle.

Why does my guitar go out of tune when I’m not even playing it?

Because of changes in temperature and humidity. Wood swells and shrinks with humidity, and the strings change tension with temperature, so a guitar goes out of tune in storage even if nobody touches it. Keep it in its case, away from radiators and direct sun.

Why does my guitar go out of tune when I use the whammy bar?

Because using the bar makes the strings slide through the nut and the string trees, and friction stops them from returning exactly to where they were. Lubricating those points and stretching the strings well helps a lot; if you rarely use the tremolo, blocking the bridge makes the guitar more stable.

Why is it always the same string that goes out of tune?

Most likely that string’s nut slot is binding, or its tuning peg is slipping. Lubricate the slot and check how the string is wound on the post.

Does a classical guitar go out of tune more than an electric?

Nylon strings take much longer to settle, so a freshly strung classical guitar seems to drift constantly for the first few days. Once they have settled, it is as stable as any other guitar.

Updated 2026-10-06