How to intonate an electric guitar: a practical guide

Spent an hour last week watching a lad at a session in Manchester absolutely murder a perfectly good solo because his guitar was fighting him above the seventh fret. Amp sounded decent, fingers were willing — but the intonation was so far out the thing was effectively playing a different song to the backing track. Broke my heart a little.

Intonation is one of those things that slips quietly, and most players don't notice until someone else mentions it. You tune up, the open strings ring true, the first few chords sound fine — and then somewhere around the twelfth fret the whole thing turns sour. That's not your tuning. That's intonation, and it's fixable at home in about half an hour with a screwdriver and a clip-on tuner.

What intonation actually means

Every fretted note is a fraction of the string's total speaking length. The twelfth fret is exactly half that length, which is why a harmonic there should ring at exactly one octave above the open string. When you fret the note physically instead of chiming the harmonic, you're stretching the string slightly — pushing it sharp. Saddle position compensates for that by making the string very slightly longer than the theoretical scale length, which pulls the pitch back down where it belongs.

Get that compensation length right and the guitar plays in tune up and down the neck. Get it wrong and it doesn't, no matter how carefully you tune before you play.

Why intonation drifts in the first place

A fresh set of strings with a gauge change is the most common culprit. Go from 9s to 10s and the increased string mass and tension means your existing saddle positions are almost certainly wrong. Same thing happens if you change tuning — drop the whole guitar down a step and you'll need to reset everything.

Nut slots that are too high are another one. A high nut makes the string travel further to reach the first few frets, which sharpens those notes disproportionately. The guitar plays flat on the nut side and increasingly sharp as you move up. That's actually a nut problem wearing an intonation costume — worth checking action at the first fret before you dive into saddle adjustments. If you're not sure what a good setup looks like end to end, our guide on how to set up an electric guitar covers the full picture.

Old strings drift too, especially wound strings that have stretched unevenly. If you haven't changed strings in a while, do that first. There's no point intonating over dead strings — you'll just have to do it again.

What you'll need

A chromatic clip-on or pedal tuner (a good one — phone apps are not accurate enough for this), a small Phillips or flathead screwdriver depending on your bridge type, and a fresh set of strings. That's it. No special tools, no luthier training required.

Play in a quiet room if you can. Harmonics are subtle and background noise makes the tuner jumpy.

The method, step by step

Tune the guitar to pitch. All strings, in standard tuning or whatever tuning you actually play in — intonate for the tuning you use. Then, one string at a time:

1. Play the harmonic at the twelfth fret. Note the pitch on your tuner.
2. Fret the same note — press it cleanly, but don't squeeze harder than you need to. Note the pitch.
3. If the fretted note is sharp relative to the harmonic, the saddle needs to move back (away from the nut), lengthening the string.
4. If the fretted note is flat, the saddle moves forward (toward the nut), shortening the string.
5. Make a small adjustment, retune to pitch, and check again. Repeat until both readings match.

Re-tune before every check. Moving the saddle affects string tension, which pulls the pitch out. Players who skip the re-tuning step chase their tail for ages — I've seen it on the bench more times than I care to remember.

Work through all six strings. The wound strings (especially the low E and A) often need the most compensation. High plain strings usually need very little.

Bridge types and how they complicate things

A vintage-style Stratocaster bridge with three barrel saddles shared between string pairs is a genuine compromise. You're setting one saddle position for two strings, so you split the difference as best you can. It's imperfect by design, and frankly I think it's the one area where the vintage aesthetic actively works against you. The six-saddle replacement bridges (Callaham make a well-regarded one) solve it properly if it's bothering you.

Tune-o-matic style bridges on Les Paul types give you individual saddle adjustment but no dedicated screw per saddle — you push or pull the saddle along a threaded rod, which can feel fiddly. Lock the adjustment with a small dab of petroleum jelly on the threads once you're happy, so vibration doesn't walk them out of position over months of playing.

Floyd Rose and other locking trems are their own world. You have to unlock the nut, make your adjustments with the fine tuners, then re-lock and re-check. If your floating bridge is significantly out of balance (springs vs string tension), sort that first — a bridge that isn't sitting level will send your intonation readings all over the place. Worth a separate session if you're new to it.

When to call a luthier instead

If you've done the process correctly and a string simply won't intonate — the saddle is already at maximum travel and the fretted note is still sharp, say — there's an underlying issue. Could be a nut cut too low, a neck with excess relief bowing the string away from the frets, or in rare cases a fret that's seated incorrectly. Those need a proper setup or a fret level, not more saddle adjustments.

Similarly, if your guitar came from the factory with a budget price tag (check price) and has never been professionally set up, there may be a stack of issues that need sorting together rather than one at a time. A full setup from a good tech — nut, truss rod, action, and intonation done in sequence — is thirty to fifty quid well spent and transforms how the instrument feels. Don't overlook pickup height either once the intonation is sorted; it's more connected to the overall setup than most players realise.

Once you've done this once you'll wonder why you ever left it. Your amp, your pedals, your technique — none of it sounds the way it should when the guitar itself is fighting the scale. Get the intonation right and everything downstream cleans up.

Right then. Screwdriver, tuner, fresh strings. You've got this.

— Jez, Amps & Valve Tone Editor