Even if you don’t understand what intonation is and how it relates to your guitar, you’ve probably experienced the tuning issues when it’s not set correctly.

Before we dive into how to adjust your intonation on the guitar, let’s take a look at the actual definition of the word. Intonation when used in general life and linguistics is essentially how your pitch can affect the meaning, or implied meaning, of what you’re saying. Intonation is all about variation in pitch.

When it comes to the guitar the use of the word ‘intonation’ is again about pitch, or what we really care about when it comes to pitch, tuning. In order for a note to be in tune across the entire range of your neck, the length between the bridge and the nut has to be absolutely perfect. Even the smallest of differences can be audible, so it’s an incredibly useful thing to know how to fix.

If you’ve ever tuned your guitar up perfectly using a tuner and open strings, for it to sound horribly out of tune when playing a note or chord further up the neck, this is exactly the sort of issue we can resolve by adjusting your intonation correctly.

How to check if your intonation is out:

Apart from being able to hear your tuning is out despite having tuned your guitar, the easiest method is to play a harmonic note at the 12^th fret, followed by a fretted note at the 12^th fret. If both are perfectly in tune you’re OK. If there’s a difference in pitch (read: tuning), then your intonation will need adjusting.

Another similar method is to tune your open strings using an electronic tuner, and then repeat the process at the 12^th fret. Notes played at the 12^th fret should be perfectly in tune as per your open strings. Whatever your method, the good news is it’s extremely easy to check.

Bridge saddles on a Fender Telecaster

How to adjust your intonation:

Thankfully, apart from in the most severe of cases, intonation can be fixed easily by adjusting the settings on your bridge saddles.

Note – if you’re making any adjustments to your action, or changing string gauges, you should do that before checking and fixing your intonation as both will have an impact.

Here’s how to adjust your intonation:

1. Tune perfectly and check how far out you are – before you start, it’s really important to get an accurate view on big your adjustments need to be. Follow the approach above, but to make sure your guitar is perfectly in tune, repeat the tuning process several times.
2. Identify saddle adjustment screws – as per the picture below, most standard electric guitars will have bridge saddles that feature adjustment screws on the back. It’s these screws you’ll need to turn in order to adjust your intonation.
3. If the note on the 12^th fret is flat – if your fretted note at the 12^th fret is flat, you’ll need to turn the adjustment screws clockwise to move the saddle forwards. Make small adjustments and check repeatedly until the note at the 12^th fret is perfect.
4. If the note on the 12^th fret is sharp – simply the opposite to the step above. If your note at the 12^th fret is sharp, turn the screw anti-clockwise to move the saddle backwards and further away from the bridge.
5. Check and repeat – it sounds obvious, but make these adjustments slowly and keep testing throughout. Take your time, and alternate between small adjustments and re-checking the tuning at the 12^th

source: fingerlakesguitarrepair.com

Fixing the most serious cases

The steps above will fix most cases of intonation issues, but in-consistent tuning across the guitar can be a symptom of more serious issues.

If your neck is slightly bent or warped then you’ll likely have tuning issues alongside other symptoms such as fret buzz at certain points on the neck.

If you’re checking and adjusting your intonation and it’s not fixing the issue, or you achieve perfect tuning at the 12^th fret, but still have the symptom on other frets, then the likelihood something else is wrong.

It’s nothing huge to worry about as most issues on the guitar (even the most serious) can be fixed quite easily, however fixes such as making neck adjustments with the truss rod should only be carried out by someone who knows what they’re doing.

At this stage, we’d definitely recommend getting the guitar checked out by an expert tech. Even if you pay for a quick check, at least you’ll know what’s going on and what needs to be done.

source: guitarmakersonline.com

Why does it change?

There are many reasons why your intonation might change over time. Once you’ve set it, it’s not something you’ll have to do daily, but from time to time it will need to be revisited particularly if you’re playing regularly or travelling with your instrument.

Changing string gauges, knocking the saddles when changing strings, adjustment screws coming loose over time, the guitar heating up and cooling down – these are all things that can change the intonation (albeit very slightly) and require you to get it looked at.

Generally speaking, if you take care of your instrument and keep on top of your routine maintenance, then it should never really become a bigger issue than one you can easily resolve yourself. 

Other useful need to know things when setting your intonation:

Beyond the steps above, there are a few more things to take into consideration when checking and setting your intonation:

Do this with new strings – old knackered strings can have a negative impact on tuning and skew your test results, meaning you might not even need to adjust the intonation in the first place. Put a new set on, and then start testing.

Stretch your strings in – once you’ve put your new strings on, make sure you’ve stretched them in so the guitar stays in tune throughout your adjustments. Otherwise you’ll be going round in circles.

Try and play evenly – playing a string too hard, or fretting your notes with too much pressure can bend the sting causing a false negative when checking your tuning. Seeing as we’re going after accuracy, make sure you play nice and evenly throughout your tuning checks.

Check multiple frets – for an even better test, try and check notes at the 5^th and 7^th frets for additional check points. No harm in being more thorough!

Tune up a semitone – a really cool tip. By increasing your string tension the accuracy in your intonation tuning. To get really accurate results, try tuning up a semitone to F, A#, D#, G#, C, F

Hope this is useful, and good luck with your adjustments!