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Last Updated: July 10, 2021
“I’ve moved my saddle is as far as it’ll go, but the stupid string still won’t intonate!”
If this sounds like you, you’ve come to the right place.
This article is for those of you who already know what intonation is and how to set it on your guitar, but you just can’t get one or two of your guitar strings to intonate properly. If it’s an electric guitar, you’ve moved the string saddle as far forward or backward as it’ll go, with no luck. If it’s an acoustic guitar, you’ve shaped the bridge saddle or tried compensated saddles, but still have a string (or strings) that are sharp or flat. What the hell is going on?
Well, there are a number of reasons that a guitar string can be stubborn. Here I’ll list them all, beginning with the most likely (and easily solved), and gradually progressing to the least likely (and more serious).
Look familiar? You’re out of room, and the string is still sharp. Maddening!
Possible Reasons a Guitar String Won’t Intonate
1. Your guitar strings are too old
If you’re struggling to set intonation on guitar strings that are already a few weeks or months old, you’re on a fool’s errand. Intonation should be set with brand new guitar strings. Why? As strings age, intonation “drifts” and you’ll naturally start to hear some out-of-tuneness across the fretboard. If this is the case, don’t adjust your intonation, just change your dang strings. Once you’ve installed and thoroughly stretched your new set of strings, then set your intonation. After that, leave it alone until your next string change. If that didn’t solve your intonation issue, read on.
2. The string’s nut slot isn’t shaped correctly
Thanks to Von Herndon (who works for Fender) for pointing this one out in the comments down below. If the nut slot isn’t filed/shaped correctly, the string will be contacting the nut slot in a bad spot, which will cause intonation issues. Rather than try to give you DIY instructions for fixing this yourself (which I’m not sure you should attempt if you’re a novice), I’ll just recommend you take your guitar in to a good tech to have this one ruled-out.
3. You have a bad guitar string (or strings)
Even with today’s technology and strict quality control methods, sometimes a few bad strings make their way into the market. So, when you have a stubborn string that simply will not intonate, replace that string with another. This will solve your issue most of the time. If not, replace it again. If you still have an issue with that string, step back and ask yourself: did you order all those strings at once, as part of a bulk pack? If so, it’s possible you got a bad batch (the strings were all manufactured in the same run, and therefore all have the same issue). If you suspect this, try a string from a completely different manufacturer. If it still won’t intonate, read on.
4. Your guitar’s pickups are too high
Remember, your electric guitar’s pickups are magnets, and fairly strong ones at that. If they’re too close to the strings, they can literally pull notes sharp while the string is vibrating. If you’ve got one or more strings that are being stubborn, try lowering your pickups a bit. If your pickup’s pole pieces are adjustable, check those first. It’s possible the pickup as a whole is okay, but you’ve just got one pole piece adjusted too close–causing that one string to be stubborn.
Measuring pickup height with my trusty PEC Tools USA Steel Ruler
Your pickup’s pole pieces should be about 2mm – 3mm away from the string–as measured with the string fretted at your guitar’s very last fret (22nd or 24th fret, depending on your guitar). Of course, this is just a ballpark measurement; you can adjust to taste. However, get pickups (or individual poles) too close to the strings and you’re bound to have intonation issues.
5. You’re setting intonation with the guitar on its back, rather than in the playing position
In case you didn’t know, you should be making “setup adjustments” like intonation with the guitar in the playing position. If you’ve been setting intonation–or doing other setup adjustments like the truss rod, string height, etc. with the guitar flat on its back or on a neck rest, then just… stop it. Gravity and other forces will play tricks on you if you make such adjustments with the guitar on its back. You’ll get everything set, then the minute you turn the guitar upright things will go slightly out-of-whack. A guitar on its back is fine for cleaning, electronics work, and other maintenance tasks, but setup adjustments (and measurements) should always be done with the guitar in the playing position.
6. When checking intonation, you’re pressing down harder/softer than you do when you actually play
This is one of the hardest things to do: when setting intonation, you should be pressing the string at the 12th fret with the same kind of force you’d use when playing naturally. This is tough because here you’re actually thinking about it, whereas when you’re playing, you’re not. This applies whether you are a heavy-handed player or tend to play with a feather touch. The pressure you use when setting intonation needs to match what you naturally do while playing.
7. You’re using the 12th fret harmonic as your reference, rather than the open string
For years I set intonation the way most of us are first taught: by comparing the fretted note at the 12th fret with the 12th fret harmonic. Then I heard guitar repair guru Dan Erlewine recommend a different way: don’t use the 12th fret harmonic as the reference note, use the open string instead. In other words, get your open string perfectly in tune, and then see whether the fretted note at the 12th fret is sharp or flat. The same adjustment rules apply, you’re just using the open string as the reference rather than the harmonic. Dan said something about the 12th fret harmonics being unreliable, but unfortunately he didn’t elaborate. Ever since then, I’ve used the open string and fretted 12th fret note to set intonation. No more harmonics for me.
You are welcome to continue using the 12th fret harmonic if you’d like. I think it’s perfectly fine in most cases. I’m just throwing this one out there for those of you frustrated with intonation issues.
8. Your guitar tuner isn’t accurate enough
The Peterson StroboPlus HD is an excellent, inexpensive strobe tuner that costs less than many guitar pedals.
Standard guitar tuners are fine for general tuning of open strings, but aren’t accurate enough for setting intonation. You need a strobe tuner accurate to within +/- 0.1 cents or better. Check your tuner’s specs, and if they don’t show you the actual accuracy numbers and simply describe it as “highly accurate”, “precise”, or something similarly vague, then you need another tuner specifically for setting intonation.
9. Your bridge saddle is tilted forward (acoustic guitars)
On acoustic guitars, and other guitars that have a single bridge saddle made of bone or plastic, the saddle should fit snugly enough in the slot that it can’t tilt forward or backward. In fact, it should take a decent bit of effort to get it in and out of the saddle slot.
This bridge saddle has tilted too far forward. Image courtesy homebrewedmusic.com
If the nut slot is too loose, the saddle will tilt forward (toward the headstock) when you tune strings up to pitch, and this tilt will throw your intonation off.
10. Your bridge saddle is worn or deeply notched (acoustic guitars)
Time for a new bridge saddle, ya think? Image courtesy sfguitarworks.com
If the nut slot is too loose, the saddle will tilt forward (toward the headstock) when you tune strings up to pitch, and this tilt will throw your intonation off.
11. Your nut is too high
Maybe you got your intonation set properly at the 12th fret, but you find that notes and chords played in the first few (lower) positions are always noticeably sharp. This is usually a sign that the guitar nut is too high. When doing a setup, it’s not uncommon (for those who are inexperienced) to forget or simply not know that setting the nut height is a part of the whole operation. If the nut is too high, the notes closest to the nut can be sharp when fretted, regardless of how precisely you set the intonation at the 12th fret.
12. Your neck is crooked (too far to one side) in the pocket
Thank you to reader Boris for reminding me about this next one…
If your neck is a bolt-on, it can be angled too far to one side or the other in the pocket, which can affect intonation. This issue is actually very common, and the good news is that it’s easy to diagnose and fix. If you notice that your high E or low E seems too close to the edge of the fretboard… or even tends to slip off the edge of the frets while you play… then your neck is probably a little crooked (angled to one side) in the pocket.
To fix this, loosen the strings till they’re almost slack, then slightly loosen the four neck bolts–just enough that the neck will move, and then pull it sideways till it’s straight. Retighten the four neck bolts.
If the neck feels like it wants to slip back the other direction before you can tighten the bolts, hold it in the correct position with one hand while tightening the bolts with the other. You may need a friend to help you with this maneuver.
13. You have too much relief (forward bow) in your neck
Having too much relief (forward bow) in your guitar neck is a double whammy: not only will it make your action excessively high, it actually shortens the physical length of the string. These two factors together will cause your fretted notes to be sharp at the 12th fret, no matter how much you try to compensate at the guitar’s bridge.
14. Your action is too high
If you just have excessively high action in-general, your fretted note at the 12th fret will always be sharp compared to the open string. No matter how far backward you move your guitar’s saddles, you just can’t get that fretted note in tune. Of course, if your action is so high that you can’t get the strings to intonate properly, then the guitar is probably unplayable anyway.
15. Your frets are excessively worn, flat, dented, etc.
Frets should be round and smooth on the top, and the string should only contact the fret at a very small point at the tip (crown) of the fret. If the tops of your frets are too flat, dented, or you just had crappy fretwork done by a bad guitar tech, you can have trouble setting intonation. If this is the case, you’ll probably have other issues too, such as fret buzz or notes fretting out.
Overly flat frets can cause intonation issues.
16. The wood around your bridge’s anchor studs has begun to oval
If you have an electric guitar with a tremolo-style bridge that rests/pivots on 2 studs, after years of string pull, the wood around these major weight-bearing studs can begin to “oval” as shown in this photo:
See that gap behind those tremolo studs? That’s a sign of ovaling. Looks like a piece of wood was wedged behind the one on the right in an attempt to stabilize it. Thanks to my reader Joe for letting me use this photo.
What was once a perfectly round hole that held the studs tightly and perfectly upright becomes an oval shape, where the studs now lean forward (toward the headstock) slightly and may even move a bit whenever you bend a string or use your tremolo.
If the wood has become so severely ovaled that the bridge studs are now quite literally in the wrong spot (too far forward), a symptom can be an inability to get your intonation right.
17. Your bridge is in the wrong position
Now we’re getting into the “rare but catastrophic” territory. You’ll usually only encounter this one on really cheap guitars or on used guitars where bad repair work was done. Rarely will a high quality guitar make it out of the factory with a bridge slightly out of place. However, I’m mentioning it because it’s something you want to be on the lookout for when buying used or “factory second” guitars. A bad repair job, where the bridge was placed just a tad too far forward/backward, can make that sucker impossible to intonate correctly. If this turns out to be the case, your only option is to have the bridge removed and relocated into the proper position. How expensive and difficult this is depends on what type of bridge it is.
18. Your nut is in the wrong position
Just as a bridge can be placed incorrectly–too far forward or backward–so can the nut. Again, it’s rare, but it is one possible cause for severe intonation problems. Again, not something that is usually seen on higher quality guitars that are brand new from the manufacturer, but be on the lookout for this if you bought your guitar used or as a “factory second.” Depending on what kind of guitar and nut you have, this one can be a little easier to fix than an improperly placed bridge.
19. Your frets are in the wrong position(s)
This one’s extremely rare and highly unlikely. It goes without saying that if your frets are slightly off, you bought a lemon. There’s no way you’re going to get this sucker to intonate properly unless you do major surgery. You’d need to pull all the frets, fill the old slots, re-cut new ones, and completely refret the guitar. Another option is to buy a whole new neck from the manufacturer or a company like Warmoth Custom Guitar Parts. However, neither of those options is realistic for a cheap guitar, as both will likely cost far more than the guitar is actually worth.
20. Your neck is too far forward or backward in the pocket
Just about as rare and unlikely as having frets in the wrong spots, if your neck was installed too far forward or backward in the neck pocket, getting correct intonation can be impossible. The good news here is that, if it’s an electric guitar with a bolt-on neck, this one can be easier to fix by a good repairperson. If it’s an acoustic, set neck, or neck-through guitar, maybe not so much. Depending on the exact nature of the problem, a pro might be able to fix this one for you, but it could be pricey. Take it in for an evaluation and estimate if you suspect this is your issue.
Some Final Thoughts and Tips
Fretted Guitars Are Imperfect Instruments
You may already know this, but I’m going to say it anyway:
Unless you’ve installed true temperament frets, you will never have perfect intonation on every note across the entire fretboard. It’s just the nature of playing an even-tempered instrument with fixed, straight fretwire.
No, you’re not hallucinating. These are True Temperament frets–the only way to get near-perfect intonation on every note across the entire fretboard. Image courtesy truetemperament.com
This is exactly why fretless instruments exist: so that the player can place their fingers in precisely the right spots and create perfectly intonated notes (which is a difficult skill to master by itself). So, get your intonation set correctly, and accept that certain notes and chords will be more in tune than others.
Consider NOT Using the 12th Fret to Set Intonation
Did you know you don’t have to use the 12th fret to set your intonation? In fact, I know people who would argue that you shouldn’t. Rather than using the 12th fret, first consider where you spend the most time on the fretboard, and then intonate your guitar for that section. So, forget about everyone else for a second and ask yourself this question:
Where do you spend most of your time on the fretboard?
Are you a campfire-chord strummer who rarely ventures above the 5th fret? If so, then it may make more sense for you to use the 3rd or 5th fret to set your intonation. If you’re a shredder who’s usually higher on the neck, then it may make sense to use the 7th, 12th, or even 15th fret to set your intonation. See where I’m going with this?
Choose to Intonate to the “Attack” or “Decay” of the Note
When you’re tuning, no doubt you’ve noticed that when you initially pluck (attack) the note, it jumps up then comes back down (decays) and stabilizes. Well, the same thing happens when setting intonation. When you pluck your reference note at the 12th fret, it’ll initially jump high then come back down.
Which should you use to set your intonation? The answer is: it depends on what playing style you use most of the time.
If you primarily play fast and rarely hold long, sustaining notes or chords, set your intonation to the “attack” note. Just be aware that, on the rare occasion you decide to hold a long note, it’ll drift a bit flat.
On the other hand, if you tend to play slower or like to hold/sustain notes and chords longer (or just let them ring out), then consider setting your intonation to the “decay” note.
What’s Missing From This List?
Okay guitar gurus, these are all the reasons that I know about. However, I’m not an encyclopedia, so if you know of any reasons that I’ve left off the list, let me (and everyone else) know in the comments below. I’ll be sure to add them to this (growing) list.
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