How to tune a guitar

What to do, in what order, and the three things that make a freshly tuned guitar go out of tune five minutes later.

Standard tuning, from the sixth string to the first

Standard tuning on a six-string guitar is E A D G B E. The strings are numbered in the opposite order to how you read that: the sixth is the thickest and lowest, the first is the thinnest and highest.

All of those frequencies come from a single number, the reference pitch: the A above middle C at 440 Hz. Everything else follows from it. If you play with a European orchestra that tunes to 442, or with an early-music group at 415, change the reference pitch on your tuner and all six strings are recalculated automatically.

The five steps

1. Tune from the sixth string to the first

Start with the thickest string. This isn't superstition: the neck bends slightly under the total tension of the strings, so every string you tighten pulls the ones you've already tuned a little off. Going from low to high, the error builds up in the least audible direction, and a second pass fixes it.

2. Play one string at a time, open

A tuner listens for one note; with two ringing at once it latches onto the louder one and shows you a number that doesn't match either. Pluck the string near the bridge, with medium force, and mute the others with your palm.

3. Come up to the note, never down to it

This is the step almost everyone skips, and the one behind most tuning problems. The string isn't held only by the tuning peg: it runs over the nut and the bridge, and it catches there. If you reach the note by loosening, part of the string ends up tighter than the tuner shows, and on the first strum that tension evens out and the note goes flat.

The fix: if you've gone past the note, loosen below it and bring it back up. Always finish by tightening.

4. Stretch new strings

A freshly installed string keeps stretching for its first few hours, and no tuning will hold through that. Gently pull it up away from the fretboard around the middle of the neck, retune, and repeat three or four times until it stops going flat. Ten minutes now saves you from what would otherwise bother you all afternoon.

5. Do a second pass

When you get to the first string, go back to the sixth. It will have moved. Two rounds are almost always enough.

How close counts as “in tune”?

The unit is the cent: one hundredth of a semitone. A trained ear starts to notice a deviation of around 5 cents on sustained notes, and quite a bit sooner when two instruments play the same note together and you hear beating.

That's why serious tuners mark a string as good within ±5 cents, rather than when the number hits exactly zero: exactly zero doesn't exist on a plucked string. The pitch rises during the attack and drops as the note dies away.

What cents are, and why tuning isn't measured in hertz →

Tuning by ear, without a tuner

The classic method is the fifth-fret method: fretting a string at the fifth fret gives you the note of the next open string. It works for every pair but one.

The method has a well-known flaw: it carries the error along. If the sixth string isn't properly in tune, the other five inherit the deviation, and the guitar ends up in tune with itself but not with anyone else. It's fine for playing alone; it won't do for playing with another instrument.

When you're in tune and it still sounds wrong

If all six open strings show green and chords higher up the neck still sound muddy, the problem isn't the tuning: it's the intonation. You check it by comparing the 12th-fret harmonic with the note fretted at that same fret; if the fretted note is sharp, the string is effectively too short and the saddle needs to move back. It's a bridge adjustment, and on an acoustic guitar it isn't always possible without a luthier's work.

Two other common causes: old strings —a worn string goes out of tune along the neck and no adjustment can save it— and pressing too hard when you fret, which stretches the string and pushes the note sharp. That last one is so common it's worth checking before you touch anything on the instrument.