How to Intonate Your Guitar

You've tuned your guitar perfectly — all six open strings read exactly 0 cents on your tuner. But when you play an actual chord or melody, something sounds wrong.

The higher up the neck you play, the more out of tune things sound. This is an intonation problem, and it's one of the most common guitar setup issues that players at all levels encounter.

Unlike basic tuning, intonation is a physical adjustment to the bridge saddles — and once it's set correctly, your guitar will play in tune everywhere on the neck.

What Is Intonation, Exactly?

When you tune a guitar string, you're setting the pitch of the open string — the full vibrating length from nut to saddle. When you fret a note, you shorten the vibrating length of the string.

The relationship between the fretted length and the open length determines the interval between them — ideally, each fret represents exactly one semitone, and the 12th fret represents exactly one octave above the open string.

In theory, this relationship is pure physics: string length halved = pitch doubled (one octave up). But in practice, several factors disturb this ideal relationship:

• String stiffness: Stiffer strings (especially wound strings and thick gauges) don't follow the ideal harmonic series precisely. They vibrate slightly sharp compared to a perfectly flexible string.
• Fretting pressure: Pressing a string down to a fret also stretches it slightly, raising its pitch. This sharp-bending effect increases with action height.
• String height (action): Higher action means longer distance to press the string down, which means more bending and more sharpening when fretted.

Intonation adjustment compensates for these factors by moving the saddle — the contact point at the bridge end of the string — slightly forward or backward.

Moving the saddle back (away from the nut) lengthens the vibrating string length, making fretted notes flatter. Moving it forward (toward the nut) shortens it, making fretted notes sharper.

What You Need to Check and Set Intonation

• A precise chromatic tuner (GuitarTunePro or a high-quality hardware tuner)
• A small screwdriver (flathead or Phillips, depending on your guitar's bridge design)
• Fresh strings (never set intonation on old strings — they won't intonate accurately)
• The correct screwdriver size for your bridge — test before starting to avoid stripping saddle screws

Step 1: Tune the Guitar

Start by tuning all six strings to pitch using your tuner. Every string should read 0 cents. This is your baseline.

Step 2: Check Intonation

For each string, do the following:

1. Pluck the open string and confirm it reads the correct note at 0 cents.
2. Gently fret the same string at the 12th fret — the metal fret, pressing firmly but not excessively.
3. Pluck the string and read the tuner. Do not touch the string between plucking and reading.
4. Compare the 12th fret reading to 0 cents:
   • Sharp (positive cents): The vibrating string length is too short — the saddle needs to move back (away from the nut, toward the strap pin end).
   • Flat (negative cents): The vibrating string length is too long — the saddle needs to move forward (toward the nut).
   • 0 cents: Intonation is correct for this string.

Step 3: Adjust the Saddle

On most electric guitars (Stratocaster, Telecaster, Gibson-style tune-o-matic, hardtail bridges), each saddle has an individual adjustment screw at the back of the bridge. Turning this screw:

• Clockwise: Moves the saddle back (lengthens string, flattens intonation)
• Counter-clockwise: Moves the saddle forward (shortens string, sharpens intonation)

Important: always de-tune the string slightly before adjusting the saddle. Moving a saddle under full string tension can strip the screw or damage the bridge mechanism. Loosen the string a half turn, make your saddle adjustment, then retune and check again.

Step 4: Retune and Recheck

After each saddle adjustment:

1. Retune the open string to 0 cents.
2. Check the 12th fret again.
3. Repeat adjustments until the 12th fret reads 0 cents (or within ±1 cent).

The process typically takes 3–5 iterations per string before you converge on the correct saddle position. Be patient — small adjustments make a big difference.

Step 5: Do a Full-Fretboard Check

After setting the 12th fret for each string, do a broader check:

• Play a barre chord at the 5th fret — does it sound in tune?
• Play the same chord shape at the 7th and 9th frets — still in tune?
• Check individual notes at the 3rd, 5th, 7th, and 9th frets on each string

If everything checks out at the 12th fret but the guitar still sounds off at lower positions, there may be nut height issues (not a saddle problem) that require nut slot filing.

Intonation on Different Guitar Types

Stratocaster / Telecaster (American Standard bridge)

Individual saddle adjustment screws at the back of the bridge. Easy to adjust. On Telecasters, the 3-saddle bridge means two strings share each saddle — perfect individual intonation is not achievable, only a compromise position.

Gibson Tune-O-Matic

Each saddle can be slid forward or backward by turning the intonation screw. Some TOM saddle slots are reversed (the thumb screw faces the neck) — check before turning to ensure you're moving the saddle in the correct direction.

Floyd Rose

Loosen the locking screw at the bottom of the saddle with an Allen key, then adjust the saddle position with the intonation screw. Re-lock, retune (including locking the nut and using fine tuners), and check. Complex but same principle.

Acoustic Guitar

Most acoustic guitars have a fixed compensated saddle. Minor adjustments can be made by a luthier who carefully files the front or back edge of the saddle to move the effective contact point. This is not reversible, so it's best done professionally.

When to Re-Intonate

• After changing string gauges
• After a significant action adjustment (truss rod or saddle height)
• After a neck reset or major repair
• If you notice chords sounding increasingly off-pitch further up the neck
• Seasonally, if neck movement from humidity changes has shifted your setup significantly

With a good setup and proper intonation, your guitar should play in tune anywhere on the neck. Use our free online chromatic guitar tuner to verify your open string tuning and to make the precise measurements needed for accurate intonation setting.

The process takes about 30–60 minutes the first time — and the improvement in playing experience is immediate and significant.