How to set the intonation on your guitar

A well-intonated guitar gives you an exact octave at the 12th fret: the string fretted there sounds exactly one octave above the same string played open. If it’s sharp or flat, chords drift out of tune as you move up the neck, even when the open strings are in tune.

You set intonation at the bridge, by making each string a little longer or shorter. On an electric guitar or a bass you can do it yourself with a screwdriver; on an acoustic or a classical, it’s a job for a luthier.

Tuning vs. intonation

Tuning is getting each open string on its note; intonation is getting the fretted notes to land in the right place too. A guitar can be in tune and badly intonated: the open strings and the first-position chords sound fine, but a barre chord at the 7th fret or a solo above the 12th sounds off.

That’s because fretting a string doesn’t just shorten it. Pushing it down to the fret also stretches it a little, which pulls it sharp. On top of that, heavier strings are stiffer and act as if they were slightly shorter. That’s why the bridge saddles don’t sit in a straight line: each string needs its own compensation, and the low strings usually sit further back than the high ones.

How to tell if your guitar’s intonation is off

You check one string at a time, comparing the 12th fret with the open string:

Carefully tune the open string.
Fret that same string at the 12th fret, just behind the fret and with your normal pressure, and check the note.
If it’s exactly an octave up, that string is fine. If it’s sharp or flat, it needs adjusting.

The ideal tool for this is a chromatic tuner that shows how many cents any note is off (a cent is a hundredth of a semitone), like a clip-on or pedal tuner. Within a couple of cents is usually considered good.

This tuner guides you through the open strings. In standard tuning, the 12th-fret note shows up as a “Free note”, with its name and its frequency rounded to the nearest Hz. The 12th fret should read double the open string’s frequency (if your A string is at 110 Hz, the 12th fret should read 220), so you can spot a big difference right away; for fine adjustment, a rounded frequency isn’t precise enough.

Before you adjust

Intonation depends on everything else, so it goes last, with the guitar set up the way you’re going to play it:

Strings in good shape. Old, rusty or kinked strings won’t intonate properly however much you adjust. If they’re due for a change, change them first and stretch them.
The gauge and tuning you’re going to use. If you change either one later, you’ll have to do it again.
Action and truss rod already set. Raising or lowering the strings changes the intonation, so that comes first.
The guitar in playing position, so you fret the way you always do.

How to set it on an electric guitar

Each string rests on a bridge saddle that a screw moves forward or back.

If the 12th-fret note is sharp, the string is too short: move the saddle away from the neck.
If the 12th-fret note is flat, the string is too long: move the saddle toward the neck.

Watch which way the saddle moves, not which way the screw turns, because depending on the bridge the same turn can move it either way. On Strat-style bridges the screws are at the back; on Tune-o-matic bridges, common on Gibsons, they’re at the front or the back depending on the model.

One string at a time: slacken the string a little so the saddle moves freely, shift it a bit, retune the open string and compare the 12th fret again. Repeat until they match. The moves are small, often less than a millimeter, and if you overshoot, the note flips to the other side.

With a floating tremolo, every time you retune a string the bridge moves a little and the others change. It takes longer, but the method is the same: retune every string before each check.

Some vintage-style Telecasters have three saddles for six strings, so each saddle is shared by two strings and you have to find the best compromise. Compensated saddles help with that.

On electric bass

Same process: tune open, compare with the 12th fret and move the saddle. Bass saddles travel further, and on the low strings the correction can be several millimeters. Tuners have a harder time reading low notes, so take your time and pluck with the same strength for every check.

Acoustic and classical guitars

On acoustic and classical guitars the bridge saddle is a fixed piece with no screws, so you can’t adjust it string by string at home. Many acoustics come with a compensated saddle, stepped or slanted, so they intonate well with the usual gauge.

If an acoustic intonates badly, the first thing to look at is the action: very high strings stretch a lot when you fret them and go sharp. If that doesn’t fix it, a luthier can reshape or replace the saddle to compensate each string.

How often to check intonation

If you stick to the same brand and gauge, you don’t need to check it at every string change. It’s worth checking:

When you change gauge or tuning, for example moving to a lower tuning with heavier strings.
After adjusting the action or the truss rod.
When the seasons change, if you notice the neck has moved.
When you buy a guitar, new or used, since you don’t know what strings or setup it was intonated with.

Frequently asked questions

What is guitar intonation?

It’s how accurately the guitar plays fretted notes, not just the open strings. A well-intonated guitar gives an exact octave at the 12th fret of every string, and chords sound in tune anywhere on the neck.

How do I know if my guitar’s intonation is off?

Tune a string open and fret that same string at the 12th fret. If the note isn’t exactly one octave higher but a little sharp or flat, that string’s intonation is off.

If the 12th-fret note is sharp, which way do I move the saddle?

Back, away from the neck, to lengthen the string. If it’s flat, the other way: move it toward the neck.

Why does my guitar sound out of tune higher up the neck when the open strings are fine?

Most likely it’s the intonation: the string length isn’t set right at the bridge. It can also come from old strings, action that’s too high, or pressing too hard when you fret.

Can I set the intonation on an acoustic guitar at home?

Usually not. An acoustic’s bridge saddle is fixed, and correcting it means reshaping or replacing it. That’s a job for a luthier, who’ll check the action first.

Updated 2026-10-08