Ultimate Guide to Guitar Intonation (With Diagrams) - Guitar Gear Finder

Ultimate Guide to Guitar Intonation (With Diagrams)

Guitar intonation is important to understand and make sure it is set properly on your guitar.

If your guitar doesn’t have intonation set up correctly, you will sound out-of-tune even if you tune your strings perfectly.

In this guide, I will explain what guitar intonation is, how to adjust it, common intonation problems and general intonation tips.

After you read this guide, I highly recommend reading these two guides to properly set up and adjust your guitar for the best results:

  • Ultimate Guide to Guitar Action. Action height and intonation impact each other, so read the guide to learn about it.
  • Ultimate Guide to Truss Rods. Once you check your guitar’s intonation and action, you may find you need to adjust your truss rod. This guide explains everything you need to know.

What Intonation Means on Guitar

Before we look at adjusting your guitar’s intonation, it is important to understand what it is and how it affects your playing.

Guitar intonation is how in-tune your guitar is along the entire fretboard length. A guitar with good intonation will be in-tune everywhere on the fretboard. A guitar with bad intonation will be out-of-tune in some areas of the fretboard.

The important point to remember is that a guitar with bad intonation can be out-of-tune even if the strings are perfectly in tune.

If you play your guitar and notice that it gradually sounds more out-of-tune the higher up the fretboard you play, that’s a sign that your intonation is out.

Let’s look at why intonation is important to get right and how to check the intonation of your guitar.

How Important is Intonation on Guitar

The best guitar in the world will sound like trash if the intonation is out.

Intonation is important to get right on your guitar to make sure you will always be in tune, regardless of where you play on your fretboard. A great guitar will sound horrible if the intonation isn’t properly set up.

If your guitar’s intonation isn’t set properly, it doesn’t matter how accurately you tune your guitar strings, you will still be out-of-tune.

The intonation of your guitar can change over time, so it is important to regularly check your intonation as explained below.

How To Check Intonation on Your Guitar

If you think your guitar’s intonation may be off, it’s quick and easy to check. Follow the below steps to check your guitar’s intonation right now:

Step 1: Tune Your Guitar

Intonation is all about how in-tune your guitar is with itself, so it is important to first tune up your guitar strings.

Tune each string as accurately as possible using a precise guitar tuner.

Check out my Ultimate Guide to Guitar Tuners for advice on the best guitar tuners available. The guide also discusses tuner apps if you don’t want to buy a tuner pedal or device.

Step 2: Play a 12th Fret Natural Harmonic

The easiest way to check your guitar’s intonation is to compare the pitch of the fretted 12th fret note to a 12th fret natural harmonic.

To play a natural harmonic on the 12th fret, lightly touch your guitar string directly above the 12th fret on the low E string as shown below:

12th fret natural harmonic

Don’t push down on the string – only lightly touch it. The string should not press against the fret.

With your tuner still on, check the tuning of the 12th fret harmonic. It should be perfectly in tune.

12th fret harmonic intonation

If it is not perfectly in tune, adjust the string until it is perfectly in tune. Having a perfectly in-tune string makes it easier to check intonation.

Step 3: Play a 12th Fret Note

Press down on the 12th fret on the low E string and play the note.

Guitar intonation flat

Check your guitar tuner to see how in-tune the note is. The tuning of this note will tell you whether the intonation is correct for this string or not. In the above example, the fretted note is flat because the note is lower than the 12th fret harmonic pitch.

If the fretted 12th fret is flat (lower than the correct pitch) or sharp (above the correct pitch), your intonation is out. The further away from in-tune the note is, the worse your intonation will be.

In the above photos, you can see that the 12th fret harmonic is perfectly in tune, but the fretted 12th fret is flat. This means the intonation is out and we need to adjust it (explained below).

If the fretted 12th fret is in-tune, it means the intonation is correct for that string. It doesn’t mean the entire guitar has good intonation, it only means that one string is correct.

Step 4: Repeat the Steps for Every String

Guitar intonation must be checked on every string on your guitar. It is possible to have some strings with perfect intonation and other strings with poor intonation.

Follow the above steps for each string on your guitar and take note of the intonation across each string.

Now that you know whether your guitar’s intonation is out on a string-by-string basis, we can look at how to adjust the intonation.

How To Adjust Intonation on Your Guitar

The way you adjust your guitar’s intonation depends on what type of guitar you have.

Intonation is adjusted by increasing or decreasing the length of a guitar string. The easiest way to do this is by adjusting the position of the guitar’s bridge.

On some guitars, adjusting the bridge position is an easy job. On other guitars such as acoustic guitars, this is almost impossible.

Which Way to Adjust Your Bridge

Before we look at different types of bridges and how to adjust each one, here are the general rules on which direction to adjust your bridge.

If the fretted 12th fret note is sharp (higher in pitch than the harmonic), you need to increase the length of the guitar string.

Increasing the length of the string will lower the pitch of the fretted note. You want to gradually increase the length of the string until the pitch of the fretted note matches the pitch of the 12th fret harmonic.

To increase the length of the string, you want your bridge saddle to move further away from the fretboard as shown in the below photo:

Increase string length intonation

The further away from the fretboard you move the saddle, the longer you make the string.

Tip: if you are increasing the length of your string, make sure you loosen the string tension before you make adjustments to prevent the string from breaking.

If the fretted 12th fret note is flat (lower in pitch than the harmonic), you need to decrease the length of the guitar string.

Decreasing the length of the string will raise the pitch of the fretted note. You want to gradually decrease the length of the string until the pitch of the fretted note matches the pitch of the 12th fret harmonic.

To decrease the length of the string, you want your bridge saddle to move closer to the fretboard as shown below:

Decrease string length intonation

Decreasing the string length will loosen the string, so you don’t need to worry about loosening it before you make an adjustment.

Fender-style Bridges

The below photo shows a fender Stratocaster bridge and other brands may use a similar style bridge:

Fender strat bridge

There are six ‘saddles’ in the bridge – one for each string. Notice that each saddle is connected to the bridge with a screw that passes through the end of the bridge.

By adjusting the screw, the saddle is pulled closer to the bridge or further away.

Turning the screw clockwise increases the length of the guitar string. If the fretted 12th fret note is sharp, adjusting the screw clockwise will improve intonation.

Increase string length intonation

Turning the screw anti-clockwise decreases the length of the guitar string. If the fretted 12th fret note is flat, adjusting the screw clockwise will improve intonation.

Decrease string length intonation

Only make small adjustments to the saddle at a time. Make a slight adjustment, then re-tune and check the intonation. Then you can decide whether you need to make further adjustments or not.

Gibson style Bridges

The below photo shows a Gibson Les Paul Tune-o-matic bridge:

Gibson bridge

You can see that each string is resting on a small roller saddle that has some room to move back or forth.

On the other side of the bridge, you will see a screw for each string. These screws adjust the position of the roller saddle.

Gibson bridge intonation

Because you access the screws from the other side of the bridge, the direction you need to turn the screw also changes compared to a Fender style bridge.

Turn the screw clockwise to decrease the string length. Do this is the fretted note is flat.

Turn the screw anti-clockwise to increase the string length. Do this is the fretted note is sharp.

Reduce the tension of the strings to prevent damaging the string or the saddles.

PRS Wraparound or Stoptail Bridges

If you have a PRS with a bridge that has saddles and screws that look similar to the Fender-style bridge as shown earlier, follow the above instructions to adjust your intonation.

If you have a PRS and the strings wrap around the bridge, a slightly different approach is needed.

PRS Wraparound bridge

Some of these wraparound bridges have adjustable saddles as shown in the above photo.

To adjust the intonation on these bridges, you need to adjust the individual screws accessed from the other side of the bridge.

It is a little awkward as you need to fit your screwdriver under the strings.

Because you access the screws from the other side of the bridge, the direction you need to turn the screw also changes.

Turn the screw clockwise to decrease the string length. Do this is the fretted note is flat.

Turn the screw anti-clockwise to increase the string length. Do this is the fretted note is sharp.

If your bridge doesn’t have individual saddles and looks like the below photo, you don’t have individual control of each string’s intonation.

PRS Stoptail bridge

While you won’t be able to adjust each individual string, you can make adjustments to the entire bridge.

There are two adjustment screws on the ends of the bridge that you can turn to angle the bridge left or right.

Stoptail adjustment screws

If all of your strings are sharp or flat, you can try to adjust the bridge position to improve intonation. But you may find that it’s close to impossible to achieve good intonation across each string.

Let’s say your high three strings are sharp. To improve intonation, you need to increase the length of those strings.

Turn the adjustment screw clockwise on the high string end of the bridge to push it away from the post.

As you can probably guess from the above photos, these types of bridges are terrible for accurate intonation adjustments.

Floyd Rose Bridges

Floyd Rose bridges do give you a way to adjust each string’s intonation, but it is awkward.

Find out more about Floyd Rose bridges in my ultimate guide here.

Floyd Rose intonation

In the above photo, you will see hex nuts that hold each saddle in place. Once these nuts are loosened, you’re able to move the saddle back or forward and re-tighten the nut.

As you might expect, this is a pain to do because of the placement of the hex nut. You first need to loosen the string to be able to loosen the nut (turn anti-clockwise). Then the string needs to be slack enough for you to physically shift the saddle.

You will likely need to detune and re-tune your guitar strings over and over as you figure out the perfect saddle position for each string.

While it is a hassle, having accurate intonation is worth the effort.

Acoustic Guitars

While there are many different types of electric guitar bridges, they all offer some way to adjust the intonation.

Acoustic guitars are different and don’t give you an easy way to adjust the intonation.

Acoustic guitar bridges

In the above photo, you can see that there is no way to adjust the position of the bridge saddle.

You can buy a ‘compensated’ acoustic saddle as shown below that offers some slight adjustment for intonation across each string.

Compensated acoustic guitar bridge saddle

Some acoustic guitarists even file their saddle down to make slight adjustments to intonation.

If you feel your intonation is slightly out, you can try compensating your saddle. If you do this, I recommend having a few spares in case it doesn’t work out.

If your intonation is out on an acoustic guitar, I recommend reviewing your action height and truss rod. The guides in those links will help you make adjustments which may solve your intonation problems.

Guitar Intonation Problems

Intonation is hard to get right on guitar because so many different things affect it.

Here are some common problems you may experience when dealing with intonation.

Bridge Saddles All the Way Back

Let’s say your intonation is sharp and you need to increase the length of the string. You adjust the saddle, re-check the intonation and it is still out.

You continue to adjust the saddle until this happens:

Bridge saddle all the way back

The bridge saddle is all the way back and the intonation is still out. You can’t adjust it any further (there is a spring that holds the saddle in place that will compress up to a point).

The first thing to do is to check the bow of the guitar’s neck. A concave bow on your neck can throw your intonation off.

Read through this guide on adjusting a truss rod to learn what to look for and how to correct a bow in your guitar’s neck.

If your neck is set up properly and the problem remains, it may be due to bad strings. The way the string contacts with the bridge saddle plays a big part in intonation, so replace your strings if the issue is only on one or two strings.

Action Height and Intonation

The action height of your guitar impacts intonation. The higher your guitar’s action, the more it will throw off intonation because the string needs to be pushed further to reach the fret.

Guitar action height and intonation

The above diagram shows how action height impacts intonation. If you have high action, you need to move the string a greater distance to reach the fret. This extra distance pushes the string out-of-tune.

The lower the action height, the less it will impact intonation. Of course, the downside of low action height is buzzing frets, so you need to work out what height is right for you.

Find out about action height here including how to adjust it to suit your playing style.

Finger Pressure and Intonation

Do you feel like every guitar you play always has sharp intonation? It may be a result of how hard you press down on the strings.

The harder you press down on a string, the higher you will push the string out-of-tune.

Finger pressure intonation

In the above photo, you can see how somebody will a light touch will end up with a different pitch than somebody with a heavy touch. The bend you see in the string from a heavy finger pressure causes the note to bend out-of-tune.

The guitar might be perfectly intonated for a light touch, but seems like the intonation is out if the guitarist has a heavy touch.

If you have a heavy touch, you will have to juggle between keeping the fretted notes in-tune and keeping the open strings in-tune.

Guitar Intonation Tips

Here are some tips to make adjusting intonation easier and get better intonation from your guitar.

Loosen Your Strings While Adjusting Intonation

If you are adjusting your bridge saddle to increase the length of your string (moving the saddle away from the fretboard), the tension in your string will increase as you adjust the saddle.

To prevent the string from breaking or damaging your saddle, de-tune the string before you make an adjustment.

If you are adjusting the bridge to decrease the length of the string (moving the saddle towards the fretboard), the string tension will decrease as you adjust the saddle. This means you don’t need to worry about de-tuning the string beforehand.

If you’re adjusting a Floyd Rose bridge, make sure the string is slack before you adjust the hex nut.

Make sure you re-tune the string before you check intonation again.

Protect Your Guitar

Any time you bring a screwdriver close to your guitar’s body, take action to protect it.

If you slip while adjusting your bridge saddles, a screwdriver can quickly ruin the finish of your guitar.

Adjusting guitar intonation

Use a folded rag or any other barrier to protect your guitar from accidental slips as shown in the above photo.

Check Your Action Height First

Before you start adjusting the intonation on your guitar, it’s a good idea to first check the action height.

Your guitar’s action height directly affects intonation. If the action is too high, it will throw your intonation out.

Check your guitar’s action height and make adjustments to action before you work on intonation.

Use a Good Tuner

Knowing how far out your intonation is makes it easier to make proper adjustments. The guitar tuner you use will either make your job easier or harder depending on how it displays the tuning.

A good tip is to pay attention to the number of Cents you are out as you make adjustments.

Let’s say your string is 20 cents out of tune. You make an adjustment to the saddle and re-check the tuning. If it is now 15 cents out, you know you can make a bigger adjustment without it going too far.

Replace Strings Regularly

As you use your guitar strings, the fret wire wears down the strings. Eventually, you might notice some flat spots on the underside of the strings that line up to the frets.

This can gradually cause intonation problems as the way the string makes contact with the fret changes.

You don’t need to replace your strings too often (read more on how often to change guitar strings here), but if you’re using super-old strings, you may find your intonation improves with a new set.

Let Your Guitar Settle

If you make adjustments to your truss rod, give your guitar time to settle before you make adjustments to intonation.

Your guitar neck needs to get used to the change in tension. Let your guitar settle for a day or two before you look at changing intonation.

Do Any Guitars Have Perfect Intonation?

If you’ve been trying to achieve perfect intonation across your entire fretboard, you may get frustrated when you find it is impossible.

Even if you manage to get perfect intonation across the 12th fret on all strings, you may find that some areas of your fretboard still have poor intonation.

It might surprise you to hear that guitars are imperfect instruments and perfect intonation is impossible on a standard guitar.

The below guitar fretboard gives you an idea of what needs to be done to overcome the intonation limitation of a typical guitar:

True Temperament frets

It’s an interesting topic, so if you want to learn more about intonation and why the above guitar has squiggly frets, check out this Guide on True Temperament Frets.

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