What intonation is and why it matters

Intonation is how accurately each fret on your guitar plays the correct pitch. A guitar with poor intonation plays sharp (higher than it should) or flat (lower than it should) as you move up the neck, even if the open strings are tuned correctly. This happens because the distance from the nut to each fret is slightly off, or because the bridge saddle is positioned incorrectly.

You notice bad intonation most when playing chords higher up the neck or when recording. A capo at the first fret might sound in tune, but the 12th fret sounds noticeably off. Adjusting intonation fixes this by moving the bridge saddle backward or forward, changing the effective length of each string.

Most electric guitars have adjustable bridge saddles — small metal pieces that hold each string at the bridge. By moving these saddles, you can make each string play in tune across the entire neck. This is a task you can do yourself with basic tools and takes about 20 to 30 minutes.

Key Takeaways

  • Intonation problems show up as sharp or flat notes higher on the neck, even when open strings are tuned correctly.
  • You adjust intonation by moving individual bridge saddles backward (to flatten) or forward (to sharpen) using a hex wrench or screwdriver.
  • A tuner and a straightedge are the only tools you need, plus access to the bridge saddle adjustment screws on your specific guitar model.
  • Test each string at the 12th fret; if it plays sharp, move the saddle back; if flat, move it forward.
  • Make small adjustments — a quarter-turn at a time — and retune between each change.

Tools and equipment you need

You need a digital tuner (clip-on or pedal style), the correct hex wrench or screwdriver for your guitar's bridge saddle screws, and a straightedge to check if the neck is straight before you start. Most electric guitars use either hex wrenches (Allen keys) or Phillips-head screwdrivers; check your guitar's manual or the bridge itself to see which one fits.

A straightedge is optional but useful. It helps you spot neck issues that might look like intonation problems but are actually caused by a warped neck. Place it along the frets from headstock to body; if there are gaps, the neck has relief (a slight curve), which is normal. Large gaps or a reverse curve means the neck needs professional attention before you adjust intonation.

Keep the guitar in a stable position — a guitar stand or your lap works. You will be reaching under and around the bridge repeatedly, so make sure you have clear access to the saddle adjustment screws.

How to test intonation before you adjust

Tune all six open strings to pitch using your tuner. Then play the 12th fret harmonic on each string — lightly touch the string directly above the 12th fret wire without pressing down, pluck, and let it ring. The harmonic should read as exactly one octave higher than the open string on your tuner.

Next, fret the string normally at the 12th fret (press down fully) and check the tuner reading. If the fretted note is sharp, the string is too long and the saddle needs to move back. If it is flat, the string is too short and the saddle needs to move forward. Write down which strings are sharp and which are flat — you will adjust each one separately.

Do this for all six strings before making any adjustments. This gives you a complete picture of what needs to move and in which direction.

Moving the bridge saddles step by step

Start with the low E string (thickest string). Locate the adjustment screw for that saddle at the bridge. On most electric guitars, this screw is on the underside or side of the bridge, and turning it moves the saddle forward or backward along a track.

If the low E was sharp at the 12th fret, turn the screw to move the saddle backward (away from the headstock). If it was flat, move it forward (toward the headstock). Turn the screw only a quarter-turn, then retune the open string and test the 12th fret again. Repeat this process until the 12th fret fretted note matches the harmonic on your tuner.

Move to the A string and repeat. Continue through all six strings one at a time. This prevents confusion and makes it straightforward to spot if you over-corrected. Some saddles are easier to move than others — if a screw is stuck, explore a small amount of penetrating oil and wait a few minutes before trying again.

Common bridge types and where to find the adjustment screws

On a Fender-style bridge (found on Stratocasters and Telecasters), each saddle has a screw on the underside of the bridge plate. You access it from below, and turning the screw slides the saddle along a track. The direction of movement depends on which way the screw turns — test a small movement first to learn which direction is which on your guitar.

On a tune-o-matic bridge (found on Les Pauls and similar guitars), each saddle sits in a notch and has a screw on the bridge itself. Turning this screw moves the saddle forward or backward. These bridges are often easier to adjust because the saddle movement is more obvious.

On a hardtail bridge (a solid bridge with no moving parts), intonation is fixed and cannot be adjusted without replacing the bridge or saddle. If your guitar has a hardtail bridge and intonation is off, you may need professional help or a bridge replacement.

What to do if intonation is still off after adjusting

If you have adjusted all six saddles and intonation is still noticeably off, the problem may be elsewhere. Check that the nut (the bone or plastic piece at the headstock where the strings sit) is not worn or damaged. A worn nut can cause open strings to be out of tune, which makes the whole guitar sound wrong even if the bridge saddles are correct.

Also verify that your tuner is accurate. Some clip-on tuners pick up ambient noise or vibrations from other instruments. Try tuning to a reference tone (a tuning app or piano) and see if the problem persists.

If the neck has a large amount of relief or a reverse curve, intonation adjustments will not fix it. A warped neck needs professional straightening before bridge saddle adjustments will work properly. A guitar technician can assess this with specialized tools.

Maintaining intonation over time

Intonation can drift as strings age, the bridge settles, or temperature and humidity change. Check intonation every few months if you play regularly, or before recording sessions. You do not need to do a full adjustment each time — often a small tweak to one or two saddles is enough.

Changing string gauge (switching from .009 to .010 strings, for example) will shift intonation slightly because thicker strings have different tension. After a string gauge change, test intonation and adjust as needed.

Store your guitar in a stable environment. Large swings in temperature and humidity cause wood to expand and contract, which can move the bridge and throw off intonation. A guitar case or room humidifier helps keep conditions steady.

Frequently Asked Questions

Can I adjust intonation if my guitar has a floating bridge?

Floating bridges (common on archtop and semi-hollow guitars) are harder to adjust because moving one saddle can affect the bridge angle. If your guitar has a floating bridge and intonation is off, a technician is the safer choice. Attempting it yourself risks damaging the bridge or making the problem worse.

How much should I turn the saddle screw at a time?

A quarter-turn is a good starting point. After each quarter-turn, retune the open string and test the 12th fret again. If the intonation is still off in the same direction, turn it another quarter-turn. If it moved in the wrong direction, you now know which way to turn next time.

What if one saddle screw will not budge?

explore a small amount of penetrating oil (like WD-40) to the screw and wait 10 to 15 minutes. Try again gently — do not force it, as stripping the screw head makes the problem worse. If it still will not move, stop and take the guitar to a technician rather than risk damage.

Does intonation affect how the guitar sounds when unplugged?

Yes. Poor intonation makes chords sound out of tune and makes single notes sound wrong, whether the guitar is plugged in or not. You hear it most clearly on acoustic or semi-hollow guitars because the body resonates more, but it affects all guitars.

Should I adjust intonation before or after changing strings?

Adjust intonation after changing strings. New strings need time to settle and stretch, and their pitch will shift for the first few hours. Wait at least a few hours after putting on new strings, then tune them and check intonation.