How to Set Up Guitar Action and Intonation
Dial in your guitar's playability and pitch accuracy by systematically adjusting neck relief, 12th-fret string height, and bridge saddle intonation.
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🧰 Required Tools & Equipment
- ✓ Truss rod hex wrench (correct manufacturer size)
- ✓ Precision string action gauge ruler
- ✓ Chromatic or strobe tuner
- ✓ Phillips #1 or small flathead screwdriver
- ✓ Guitar capo
- ✓ Feeler gauge set (specifically .010 inch / 0.25 mm)
📦 Materials & Supplies
- ✓ Fresh set of guitar strings
- ✓ Soft microfiber work mat
- ✓ Guitar neck support rest or rolled towel
⚠️ Safety Checkpoints & Warnings
- • Never force a truss rod that resists turning; excessive torque can snap the rod or crack the neck wood.
- • Keep your face away from the string plane when tuning to pitch to avoid injury if a string snaps.
- • Support the guitar neck evenly on a padded cradle to prevent dropping or stressing the headstock joint.
📋 Step-by-Step Guide (6 Steps)
Measure Neck Relief with Capo and Feeler Gauge
Tune the guitar to standard pitch and place a capo securely across the 1st fret. Fret the low E string with your right pinky at the fret where the neck joins the body (usually the 14th to 17th fret). Slide a .010-inch (0.25 mm) feeler gauge between the top of the 8th fret crown and the bottom of the low E string; it should touch both surfaces with only slight friction.
- • Feeler gauge slips cleanly beneath the 8th fret low E string with a light brush against both metal surfaces.
- • Capo clamped squarely behind fret wire without choking the string.
- • Measuring neck relief with the guitar laying flat on its back instead of held in playing position.
- • Using a gauge too thick that physically lifts the string off its resting height.
Adjust the Truss Rod for Target Relief
Locate the truss rod access point at either the headstock or the neck heel, inserting the exact-sized hex key completely into the socket. If the gap at the 8th fret was greater than .010 inches (excessive bow), turn the wrench clockwise (tightening) by no more than 1/8 to 1/4 turn. If the string touched the 8th fret without a gap (backbow), turn the wrench counter-clockwise (loosening) by 1/8 to 1/4 turn, then retune and recheck relief.
- • Wrench seated fully into the truss rod nut before turning.
- • String clearance at the 8th fret measures exactly .010 inches after retuning.
- • Turning the truss rod more than a quarter-turn at a time without letting the neck settle.
- • Stripping the truss rod nut by using a metric wrench on an imperial socket or vice versa.
Measure 12th-Fret String Action Height
Remove the capo and ensure every string is precisely tuned to concert pitch. Place the bottom edge of your string action gauge perpendicular against the 12th fret wire right next to the low E string. Read the measurement from the top of the 12th fret crown to the bottom of the string, then repeat the measurement on the high E string.
- • Base of the action ruler resting flat across the 12th fret crown.
- • Measurement lines clearly visible directly behind string under bright lighting.
- • Measuring to the top of the string instead of the bottom edge.
- • Taking action measurements while the guitar is out of tune, which alters neck tension.
Adjust Bridge Saddle Height for Action
Standard electric action targets roughly 4/64 inch (1.6 mm) on the high E string and 5/64 inch (2.0 mm) on the low E string. For individual saddles (e.g., Strat/Tele style), use the bridge adjustment hex key to raise or lower both height screws evenly until matching your target height. For tune-o-matic bridges (e.g., Les Paul style), use a flathead driver or thumbwheels to raise or lower the treble and bass bridge posts while strings are slightly slackened.
- • Both set screws on individual saddles sit level with no uneven tilt.
- • Action ruler confirms 4/64 inch clearance on high E and 5/64 inch clearance on low E.
- • Tilting individual saddles sideways by adjusting only one of the two height screws.
- • Adjusting bridge height without retuning before taking the final measurement.
Set Bridge Saddle Intonation
Plug the guitar into your chromatic tuner and tune the low E string to exact concert pitch. Lightly touch the string directly over the 12th fret wire and pluck to sound the natural 12th-fret harmonic, ensuring the tuner reads dead center. Next, press the string firmly against the 12th fret and pluck; if the fretted note is sharp compared to the harmonic, turn the saddle screw clockwise to move the saddle back toward the tailpiece; if flat, turn counter-clockwise to move it forward toward the pickups.
- • 12th-fret harmonic and 12th-fret fretted note both hit dead center green on the tuner display.
- • Saddle moves smoothly along its track without binding against adjacent saddles.
- • Pressing too hard on the 12th fret, artificially bending the string sharp during testing.
- • Using worn, old strings which possess inconsistent mass and will not intonate properly.
Perform Full Fretboard Playability and Buzz Test
Pick every note chromatically along each string from the 1st fret all the way up to the highest fret. Listen through a clean amplifier setting for any buzzing, rattling, or notes that choke out during whole-step bends on the 12th through 15th frets. If a specific bend chokes out on the upper frets, raise that string's saddle height by 1/64 inch and verify the clean ring.
- • Every note rings out cleanly with sustained decay and no metallic rattling against higher frets.
- • Whole-step bends on treble strings sustain cleanly past the 12th fret without fretting out.
- • Testing fret buzz on an unplugged electric guitar where natural acoustic vibration can be mistaken for audible amplifier buzz.
- • Over-raising the action to fix fret buzz caused by an uneven single fret instead of neck geometry.
Don’t have everything?
- No Feeler gauge? Standard business card or paper cardstock (approx. 0.010 inch thickness)
- No String action gauge? Precision metal machinist ruler marked in 1/64-inch or 0.5 mm increments
- No Capo? Pencil strapped tightly behind the 1st fret with two rubber bands