These two ideas are related but not interchangeable. Tuning is an everyday player adjustment. Intonation is a setup adjustment, usually made at the bridge.
If an open chord sounds fine but a chord at the twelfth fret sounds wrong, intonation may be the reason. Tuning adjusts the open strings. Intonation describes whether fretted notes remain accurate as you move along the neck. A guitar can therefore show perfect open strings on a tuner and still sound wrong in higher chords.
Tuning
Use the tuning machines to set E, A, D, G, B and E. This changes the tension and pitch of the whole string.
Intonation
The bridge saddle changes the effective string length. Correct length allows the fretted notes to line up with the musical scale.
The twelfth-fret comparison is a useful test
The twelfth-fret harmonic represents the ideal octave point. Compare it with the fretted twelfth-fret note. If the fretted note is sharp or flat, the effective string length at the bridge may need adjustment.
Why setup matters
String gauge, action and neck relief affect intonation. Change these first, then set intonation last.
Playing pressure also affects the test
Pressing too hard can pull a fretted note sharp, especially with tall frets or light strings. Use normal playing pressure and a fresh, well-stretched string before judging the setup.
Tune and check the result
- Always tune before testing intonation.
- Use fresh or reasonably healthy strings.
- Press with normal force; excessive pressure can make the note sharp.
- If you are unfamiliar with saddle adjustment, let a technician perform the setup.
- Tune the open string exactly, then compare the twelfth-fret harmonic and fretted note.
- Repeat the test on every string because each saddle may require a different position.
When the guitar still feels wrong
You keep retuning but high chords remain wrong
Open-string tuning cannot correct a string-length problem. Test intonation at the twelfth fret.
The result changes with old strings
Worn strings can intonate unpredictably. Replace them before making precise setup decisions.
Intonation changes again after new strings
Different gauges and old or damaged strings alter how the note behaves. Set intonation with the string type and tuning you intend to use regularly.