I'm pretty frustrated because I just got done reading multiple "fix your intonation" articles on the internet and it seems there's a recurring gap in the explanations. I now know that if I have an intonation problem, it may be having the wrong strings, nut height, bridge height, saddle position, or even truss adjustment/neck relief issue. I also now know that high action can cause intonation problems.

What I still do NOT know because all the articles I read in the last hour fail to say, is WHICH WAY these problems affect your intonation. Does lowering your action sharpen the intonation (to fix it if your intonation is flat at the 12th fret), or the opposite? Okay, I did find something telling me which way to move the saddles to fix sharp versus flat intonation, but that's it.

My intonation is very flat, meaning that if I tune my open E right on, my 12th fret is very flat -- like halfway between D# and E. And the other strings have a similar problem. The problem is so drastic, that I am quite sure fiddling with the saddles is not going to correct his, and I need to look elsewhere. But I don't know if raising the bridge will sharpen or flatten my intonation. Or which way changing nut height affects intonation (higher = flatter or sharper?). Or whether increasing neck relief would make intonation sharper or flatter.

I guess I can just start adjusting things one way, and go back checking the intonation to see how it has been changed, till I figure this out for myself. But it just seems like reinventing a wheel that has surely been invented countless times before. I'm rather annoyed the brainy, experienced guitarists who wrote the articles that come up highest on a google search of this issue, with titles like, "The basics of fixing your intonation" do not impart this fundamental knowledge. Telling me the height of the action can "affect" my intonation is like telling some one with a dangerously high fever that sugar intake can "affect" body temperature, when they clearly need to know if more sugar will "raise" or "lower" temperature, or vice versa. Merely saying it "affects" temperature is pretty clueless. I feel like the various "fix your intonation" articles I read in the last hour were all kind of like that.

So if anyone can break down for me WHICH WAY things need to be adjusted to make intonation go flatter or sharper, I'd appreciate it greatly, so I don't have to throw in the towel and just start fiddling till I figure this out.

Last edited by krm27 at Nov 18, 2014,
You don't see that very often specified because it doesn't matter. And it can go either way. All that actually matters is that you know how to adjust intonation via the saddles. Adjust everything else (neck relief, string gauge, action, etc.) to a point that it feels good to you, regardless of intonation. Then check your intonation and if it's off, either way, just fix it with the saddles.
what he said, none of them matter as much as the saddles because they affect the string length the most. that's what you're changing when "adjusting intonation", the strings' length from the saddle to the nut. that length is relative to your gutiars scale

string height is a mater of how you like to play, low and close to the neck plays "faster" but more prone to fret buzz, playing too high is only good for playing with slides. also too close to the pickups and they muddle the sound, or too far and too soft sound XD that's why you can also adjust the pick up heights.

also the truss is like the last thing you should fiddle with, a bent neck is the worst, but it only happens if you ship your guitar around a lot on airplanes, and there's constant air pressure and moisture changes or whatever else causes that. and adjusting the nut is doable but only really needed on acoustic guitars because they usually don't have adjustable saddles.

THATS also why these things dont need to be adjusted tooo much, its crazy and they come out of the factory well enough most of the time. you could get your guitar professionally intonated by computer, which adjusts all these. but its like $150.00 last i checked.

intonation is commonly off, because you change strings or the saddles jiggle.

tl dr, if you're having problems intonating your guitar with the saddles alone, try starting with them as far forward as they go towards the pickups, because then you can go back as needed. if theyre allready too far back, well, you know, they cant go back any further , they cant pull over any further!
If your intonation is flat you should move the saddles toward the pickups. An higher action should make the intonation go sharper, because when you fret the string you're slightly bending it, and you bend it more if the action is higher.
To check if there's a problem with the nut I'd try to intonate at the first fret instead of with the open string, if you can get a good intonation on the fretted notes but not with an open string that's a sign that the string might leave the nut in the wrong position (or that your action is too high).
Hope I didn't write anything blatantly wrong
1st step - new strings.
2nd step - Set up your action (string height & neck relief) so that it feels comfortable to you and doesn't buzz too much.
3rd Step - compare the open string note to the fretted 12th note, they should be the same only 1 octave apart. This method (D Erlewine) is better in my experience than the Fretted 12th and harmonic on the 12th.
If the fretted 12th is sharp move the saddles back, if the fretted 12th is flat move the saddle forwards.
I've moved all the saddles all the way toward the pickups. As suspected, this gave negligible relief because most of the saddles were already pretty far in that direction and, as I said, the note is flat by like half a semitone (a quarternote) by the 12th fret. In my experience, a quarternote might be the max change you'll get in intonation at the 12th fret moving a saddle all the way from one side to another so, here, where my saddles were in the middle or closer to the pickups already, I had a strong hunch saddle adjustment would be futile.

Reading that raised action sharpens intonation, I raised the bridge somewhat. This did sharpen the strings across the board. So they were sharpened when open, too. Once I re-tuned the open strings back down to the correct pitch, and re-checked intonation, I saw no significant change. So assuming it's not a myth that raising the bridge will sharpen intonation, it does appear that it is a very minor change, and I'd have to raise the action to a ridiculous height to add a quarternote of sharpness at the 12th fret relative to the open pitch.

The strings intonate fine in the 1st five frets, the problem appears around the 6th fret and worsens as you move toward the bridge, so I think this rules out the nut at the problem.

Any other suggestions?

Messing with the action trying to cover up an intonation problem isn't a good idea, I'd try first to change the strings, especially if they are old.
It is the first time you try to intonate that guitar? The bridge could be in the wrong position

Thanks a bunch, that was the problem. This is my first jazz-box type electric, did not realize the bridge was movable. I'm guessing it got knocked out of position during shipping (when the strings were de-tuned). Now my intonation is spot on.

Quote by krm27

Thanks a bunch, that was the problem. This is my first jazz-box type electric, did not realize the bridge was movable. I'm guessing it got knocked out of position during shipping (when the strings were de-tuned). Now my intonation is spot on.


Oh snap. Yeah, that'll do it. Hahaha. With a guitar like that, the bridge should be the same distance from the 12th fret, as the the 12th fret to the nut.