What string action is and why you adjust it

String action is the distance between your strings and the fretboard. When action is too high, the strings sit far from the frets, making the guitar harder to play because you have to press down harder. When action is too low, the strings buzz against the frets when you play, creating an unwanted metallic sound. The goal is to find the middle ground where the strings ring clearly without requiring excessive finger pressure.

Most electric guitar players prefer lower action than acoustic players do, because electric guitars are easier on the fingers and the amplifier masks some buzzing. A typical target is around 2mm on the bass side (thicker strings) and 1.5mm on the treble side (thinner strings) at the 12th fret, though this varies by player preference and playing style.

You adjust action by changing the height of the bridge, the nut, or both. On most electric guitars, the bridge is adjustable and that is where you start. The nut is harder to adjust and usually requires a specialist, so this guide focuses on bridge adjustment.

Key Takeaways

  • String action is the gap between the strings and fretboard, and you measure it at the 12th fret using a ruler or feeler gauge.
  • Most electric guitars have an adjustable bridge with saddles that raise or lower to change action height.
  • Always loosen the strings before making bridge adjustments, and make small changes—a quarter turn at a time—because the effect compounds.
  • If action is still too high after lowering the bridge all the way, the nut may be too tall and you will need a professional repair.
  • Buzzing that happens only on certain frets usually means the neck needs a truss rod adjustment, not a bridge adjustment.

Measuring action before you start

Before you adjust anything, measure your current action so you know where you are starting. Use a metal ruler or a feeler gauge (a set of thin metal blades used to measure gaps, available at hardware stores for under $10). Place the ruler flat across the frets and measure the gap between the bottom of the string and the top of the fret at the 12th fret, which is roughly in the middle of the neck.

Measure each string separately—bass strings on one side, treble strings on the other—because they may not be at the same height. Write down the measurements. This gives you a reference point so you can tell whether your adjustments are working.

If you do not have a feeler gauge, a standard ruler works, but feeler gauges are more accurate because the blades are thinner and fit between the string and fret more easily. You can also use a capo at the first fret and hold down the last fret to see the gap more clearly, though this is less precise than measuring.

Locating and understanding your bridge type

Electric guitars use several bridge types, and the adjustment method depends on which one you have. The most common on modern guitars is a bridge with individual saddles—each string sits on its own small piece that can be raised or lowered. Fender Stratocasters and Telecasters use this design. Some guitars have a tune-o-matic bridge (common on Les Pauls), which has two posts that raise or lower the entire bridge at once. A few guitars have a hardtail bridge with no moving parts, which means you cannot adjust action at the bridge and must adjust the nut instead.

Look at your bridge from the side. If you see small screws or hex bolts on either side of the bridge, you likely have an adjustable bridge. If the bridge is a solid piece with no visible adjustment points, check your guitar's manual or search the model name online to confirm the bridge type before proceeding.

Loosening strings and adjusting individual saddles

Always loosen your strings before adjusting the bridge. Tuning tension holds the bridge in place, and trying to adjust under full tension risks stripping screws or damaging the bridge. Loosen all strings by turning the tuning pegs until the strings are slack—you do not have to remove them completely, just enough that they are loose.

On a bridge with individual saddles, you will see a small screw or hex bolt on each saddle, usually on the bridge plate underneath or on the side. Use the correct screwdriver or hex wrench (typically 1.5mm or 2mm) and turn clockwise to raise the saddle, counterclockwise to lower it. Make very small adjustments—a quarter turn at a time—because even a small turn changes the action noticeably. Adjust all saddles equally first to see the overall effect, then fine-tune individual strings if needed.

After each adjustment, retune the strings to pitch and measure the action again. This cycle takes time, but rushing leads to overshooting and having to adjust back. If you are lowering action, go slowly until you hear a little buzzing, then raise it slightly until the buzz stops. That is usually the sweet spot.

Adjusting a tune-o-matic or two-post bridge

A tune-o-matic bridge has two posts (one on each side) that raise or lower the entire bridge together. You will see a hex bolt or screw on top of each post. Loosen your strings first, then use the correct hex wrench or screwdriver to turn both bolts equally. Turn clockwise to raise the bridge, counterclockwise to lower it. Because both posts move together, the action changes evenly across all strings.

Make quarter-turn adjustments on both posts, retune, and measure. If one side of the bridge sits higher than the other after adjustment, the posts may not be turning at the same rate—stop and check that both bolts are the same size and that you are turning them with equal pressure. Uneven bridge height can cause intonation problems, so take time to get both sides level.

When the bridge is at its limit

If you have lowered the bridge saddles all the way and action is still too high, the problem is usually the nut—the small piece at the headstock end where the strings sit. The nut is cut to a specific height, and if it is too tall, lowering the bridge will not help. At this point, you need a professional luthier or guitar repair technician to file the nut down.

Do not attempt to file the nut yourself unless you have done it before. The nut is small, the tolerances are tight, and mistakes are expensive to fix. A professional can measure your action goal, file the nut to the right height, and may support the string slots are still properly shaped so the strings do not rattle or slip.

Similarly, if you have raised the bridge all the way and action is still too low with buzzing, the neck may need a truss rod adjustment to add back-bow (a slight curve that lifts the middle of the fretboard). Truss rod adjustments are also best left to professionals because over-tightening can crack the neck.

Checking intonation after action adjustment

After you have set your action, check your intonation—whether the guitar plays in tune across the fretboard. Use a tuner and play the open string, then play the same note at the 12th fret (one octave higher). If the 12th fret note is sharp (higher in pitch), the saddle may be too far back; if it is flat (lower in pitch), the saddle may be too far forward. Some bridges allow you to adjust saddle position forward and back as well as up and down.

Intonation adjustment is separate from action adjustment, but the two are related because moving a saddle up or down can also move it slightly forward or back. If you notice intonation problems after adjusting action, you may need to fine-tune saddle position. Check your guitar's manual for the correct procedure, as it varies by bridge type.

Frequently Asked Questions

How do I know if my action is too high or too low?

Action is too high if playing feels uncomfortable or your fingers hurt after a short session. Action is too low if you hear buzzing when you play, especially on open strings or the first few frets. The buzzing sound is the string hitting the frets. Measure at the 12th fret and compare to the typical range (around 2mm bass, 1.5mm treble) to see where you stand.

Can I adjust action without loosening the strings?

You can make very small adjustments with strings at tension, but it is risky. Loosening the strings takes five minutes and removes the risk of stripping screws or damaging the bridge. Always loosen first.

Why does my guitar buzz on only a few frets?

Buzzing on specific frets usually means the fretboard has a dip or high spot, not that action is too low overall. This is a neck issue, not a bridge issue, and requires a truss rod adjustment or professional fret leveling. Lowering the bridge further will not fix it.

Do I need special tools to adjust my bridge?

You need a screwdriver or hex wrench that fits your bridge bolts (usually 1.5mm or 2mm), a ruler or feeler gauge to measure, and a tuner. A feeler gauge is helpful but not required. Most of these are tools you may already have, or they cost under $15 total.

What if I adjust the bridge and the strings go out of tune?

This is normal. Changing bridge height changes string tension slightly, so retune after each adjustment. This is why you make small changes and retune between each one—it lets you see the effect clearly and catch problems early.