Guitar Intonation: Why Your Guitar Sounds Out of Tune (and How to Fix It)

You’ve tuned your guitar perfectly - every open string matches the tuner. But when you play a barre chord at the 12th fret, it sounds wrong. Or chords at the 5th fret sound slightly off. Your guitar has an intonation problem.

Intonation is the guitar’s ability to play in tune across the entire fretboard, not just at open strings. Bad intonation means proper tuning at the open position but increasingly wrong notes as you move up the neck.

What Causes Bad Intonation?

The Physics

When you push a string against a fret, you slightly stretch it - raising its tension and therefore its pitch. This sharpening effect increases as you move up the neck because fretting requires more stretch at higher positions.

Guitar manufacturers compensate for this by angling the saddle (on acoustics) or using individually adjustable saddle pieces (on electrics). When this compensation is incorrect, intonation suffers.

Common Causes:

• String age: Old strings lose uniform density, causing uneven vibration
• Incorrect saddle position: The saddle needs to be set for your specific string gauge
• Action too high: High action increases the stretch needed to fret, sharpening notes
• String gauge change: Switching from .009 to .011 without adjusting intonation
• Worn frets: Uneven fret heights change effective string length

How to Check Intonation

The 12th Fret Test

1. Tune your open 1st string perfectly to E using a tuner
2. Play the harmonic at the 12th fret (lightly touch the string directly over the fret wire and pluck)
3. Play the fretted note at the 12th fret (press normally)
4. Compare: the fretted note and harmonic should be the SAME pitch

If the fretted note is SHARP: The string length is too short. The saddle needs to move AWAY from the nut (back toward the bridge).

If the fretted note is FLAT: The string length is too long. The saddle needs to move TOWARD the nut (forward).

Tolerance

Perfect intonation is nearly impossible on guitar due to the physics of tempered tuning. A few cents off (2-3 cents) is acceptable and normal.

How to Adjust Intonation

Electric Guitar (Adjustable Saddles)

Most electric guitars have individual saddle pieces with adjustment screws:

1. Tune the string open
2. Check the 12th fret (fretted vs harmonic)
3. If sharp: Turn the saddle screw to move the saddle AWAY from the neck (lengthen the string)
4. If flat: Turn the saddle screw to move the saddle TOWARD the neck (shorten the string)
5. Retune the open string after each adjustment
6. Recheck at the 12th fret
7. Repeat until fretted and harmonic match

Small adjustments - quarter turns of the screw - make significant differences.

Acoustic Guitar (Fixed Saddle)

Acoustic intonation is harder to adjust because the saddle is usually a single piece of bone or plastic:

• If slightly off: New strings and a professional setup may resolve it
• If significantly off: The saddle may need to be replaced or recompensated by a luthier
• Compensated saddles: Some acoustics use saddles with built-in angles that improve intonation. Upgrading to a compensated saddle is the best DIY fix

When to See a Professional

If you’re not comfortable making these adjustments, a guitar tech can set intonation during a standard setup ($40-60). This is recommended for acoustic guitars especially.

Prevention

1. Change strings regularly. Old strings have inconsistent mass distribution that causes intonation issues.
2. Use the same string gauge. Every time you change gauge, intonation needs readjusting.
3. Get annual setups. Temperature and humidity changes throughout the year affect neck relief, action, and intonation.
4. Don’t press too hard when fretting. Excessive pressure pushes strings sharp.

Common Mistakes

1. Only tuning open strings. If your intonation is off, open strings being in tune means nothing - everything up the neck is wrong.

2. Ignoring intonation on acoustic. Acoustic intonation issues are common and fixable. Don’t live with a guitar that sounds off at the 5th fret.

3. Making large adjustments. Tiny movements of the saddle make big pitch changes. Quarter-turn adjustments and recheck.

Try This in Guitar Wiz

Use the Tuner in Guitar Wiz to check intonation - tune the open string, then check the 12th fret fretted note. The precise pitch display shows exactly how many cents sharp or flat the fretted note is, making intonation checks quick and accurate.

Download Guitar Wiz on the App Store · Explore the Guitar Tuner →

FAQ

Can bad intonation be fixed?

Yes. On electric guitars, it’s a simple saddle adjustment. On acoustics, it may require a new compensated saddle or professional setup.

How often should I check intonation?

Every time you change string gauges, get a setup, or notice chords sounding “off” up the neck. Every 6-12 months for regular maintenance.

Does intonation matter for beginners?

Somewhat - bad intonation can make learning harder because chords sound wrong even when finger positions are correct. A basic setup addresses this.

People Also Ask

Why does my guitar sound out of tune even after tuning? Most likely an intonation issue. The guitar can be perfectly in tune on open strings but progressively out of tune as you move up the fretboard.

How do you check guitar intonation? Compare the pitch of the 12th fret harmonic with the 12th fret fretted note. They should match. If they don’t, intonation adjustment is needed.

How much does guitar intonation adjustment cost? DIY is free (electric guitars with adjustable saddles). Professional setup including intonation runs $40-60.