Intonation means adjusting the bridge saddles so each string plays the correct pitch when fretted

Intonation is the adjustment that makes a fretted note play at the right pitch. When you press a string down on the 12th fret, that note should be exactly one octave higher than the open string. If it's sharp (higher) or flat (lower), the bridge saddle needs to move. Moving the saddle backward makes the note flatter; moving it forward makes it sharper. This is different from tuning the tuning pegs—tuning pegs set the open string pitch, while intonation fixes what happens when you fret the string.

You need a digital tuner (clip-on or pedal style, around $15–$40) and an Allen wrench or screwdriver that fits your bridge saddle screws. Most electric guitars have saddle adjustment screws on the bridge—usually one screw per string on Fender-style bridges, or a single screw per saddle on other designs. Check your guitar's manual or bridge type to know which tool you need.

Intonation drift happens because string gauge, temperature, and playing wear all change how the string vibrates. A guitar that was intonated perfectly six months ago may be off now. You should check intonation every few months, or whenever you change strings.

Key Takeaways

  • Intonation is adjusted at the bridge saddles by moving them forward or backward, not by turning the tuning pegs.
  • You measure intonation by comparing the open string pitch to the 12th-fret harmonic, then to the fretted note at the 12th fret.
  • If the fretted 12th-fret note is sharp, the saddle moves backward; if it's flat, the saddle moves forward.
  • A digital tuner and the correct Allen wrench or screwdriver are the only tools you need.
  • Intonation should be checked every few months or after a string change, because it drifts over time.

Tune the open strings first, then measure the 12th fret

Start with your guitar tuned to pitch using the tuning pegs. Use your digital tuner on the headstock or plug in a tuner pedal. Tune each string to its correct open pitch—low E, A, D, G, B, high E.

Once the open strings are in tune, clip your tuner to the headstock or set up your tuner pedal. Pluck the low E string open and note the pitch reading. Then press the low E string down at the 12th fret and pluck it. The tuner should read exactly one octave higher than the open string—if your open E is E2, the 12th fret should be E3. If the fretted note reads sharp (higher than it should), the saddle is too close to the neck and needs to move backward. If it reads flat (lower), the saddle is too far from the neck and needs to move forward.

Repeat this for each string: open pitch, then 12th-fret pitch. Write down which strings are sharp and which are flat so you know which saddles to adjust.

Adjust the saddle screws one quarter-turn at a time

Locate the saddle adjustment screw for the string you're working on. On a Fender Stratocaster or Telecaster, there is one screw per saddle, usually on the back of the bridge plate. On a Gibson-style tune-o-matic bridge, there is one screw per saddle on the side. On a Floyd Rose or locking bridge, the saddle adjustment may be a small screw or hex key on the saddle itself.

Insert your Allen wrench or screwdriver into the saddle screw. Turn it one quarter-turn only. Turning too much at once overshoots the adjustment and wastes time. If the 12th-fret note was sharp, turn the screw to move the saddle backward (away from the neck). If it was flat, turn the screw to move the saddle forward (toward the neck). The direction depends on your bridge design—test a quarter-turn and listen to whether the note got sharper or flatter, then adjust your next turn accordingly.

After each quarter-turn, pluck the string open, then pluck it at the 12th fret, and check the tuner reading again. Stop when the 12th-fret note matches the open string pitch exactly (one octave higher). This usually takes two to four quarter-turns per string.

Check the 12th-fret harmonic as a reference point

Some players use the 12th-fret harmonic as a reference instead of the open string. A harmonic is a bell-like tone you get by touching the string lightly at the 12th fret without pressing it down, then plucking. The harmonic should be exactly in tune with the open string. If your tuner shows the open string is in tune but the 12th-fret harmonic is off, your tuning pegs may need adjustment, not the bridge saddles.

The harmonic method is useful as a sanity check: if the open string and the 12th-fret harmonic are both in tune, but the fretted 12th-fret note is off, you know the problem is the saddle position, not the tuning peg. This saves you from chasing the wrong adjustment.

Work through all six strings systematically

Intonation is easiest when you adjust one string at a time and finish it before moving to the next. Start with the low E string, get it perfect, then move to A, then D, then G, then B, then high E. This way you avoid the confusion of jumping around and forgetting which strings you've already done.

As you adjust each saddle, the bridge may shift slightly, which can throw off strings you've already intonated. This is normal. If you notice a string you finished earlier is now off again, go back and fine-tune it. Usually one or two more quarter-turns brings it back in. The bridge settles after a few adjustments, so the later strings are usually more stable than the first ones you did.

If you have a tremolo arm (whammy bar), test intonation with the arm at rest in its normal position. Some bridges shift slightly when the arm is used, so you may need to find a middle ground where intonation is acceptable both at rest and after light use.

When to call a professional instead of adjusting yourself

If your saddle screws are stripped (the wrench spins without turning the screw), or if the saddle won't move even after multiple full turns, the bridge may need professional service. A luthier or guitar tech can replace the saddle, re-cut the saddle slot, or repair the bridge mechanism—work that is beyond a home adjustment.

If you've adjusted the saddles to their physical limits (all the way forward or all the way backward) and the guitar still won't intonate, the neck may have a problem, or the bridge itself may be misaligned. A tech can measure the neck relief and bridge position and determine whether the issue is fixable or requires a new bridge. This is not something to force on your own.

If you're uncomfortable using tools on your guitar, or if you've never done this before and want to see it done once, a tech can intonate the guitar for you in 15 to 30 minutes. The cost is usually $30 to $60, depending on your area and the bridge type.

Frequently Asked Questions

Do I have to intonate every time I change strings?

Yes. New strings settle into the bridge and nut differently than old ones, and the gauge or material may be different. Always intonate after a string change, even if you use the same gauge. It usually takes 10 to 15 minutes once you know how.

What if I adjust the saddle and the string goes out of tune?

That's normal. When you move the saddle, the string length changes, which changes the open string pitch. Retune the open string with the tuning peg, then check the 12th fret again. You may need to go back and forth a few times before both the open string and the 12th fret are in tune.

Can I intonate a guitar with a Floyd Rose bridge?

Yes, but it's more involved because the Floyd Rose is a locking system. You'll need to unlock the nut at the headstock, intonate at the saddles, then re-lock the nut. Some players find it easier to have a tech do this. If you want to try it yourself, consult your guitar's manual for the exact unlock and lock procedure.

Why does my guitar go out of intonation so fast?

Temperature changes, heavy playing, and string wear all cause intonation drift. If your guitar is near a heater or in a cold room, the wood expands and contracts, moving the bridge slightly. If you bend strings a lot, the saddle can shift. Check intonation every few months as routine maintenance.

Is intonation the same as action?

No. Action is the height of the strings above the fretboard, adjusted at the nut or bridge. Intonation is the pitch accuracy when you fret a note. You can have good action and bad intonation, or vice versa. They are separate adjustments.