What guitar action is and why it matters
Action is the distance between your strings and the fretboard. High action means the strings sit far from the wood; low action means they sit close. This distance affects how hard you have to press to play a note, how easily the strings buzz against the frets, and whether your guitar feels comfortable to play.
Most players prefer action somewhere in the middle—low enough that you don't exhaust your fingers, high enough that the strings don't rattle. Electric guitars typically have lower action than acoustic guitars because the pickups are closer to the strings and buzz less. The "right" action is personal: some players like it low and straightforward, others prefer it higher to avoid buzz.
Action is set at two points: the nut (where the strings start at the headstock) and the bridge (where they anchor at the body). Most adjustments happen at the bridge, which is easier to modify without special tools.
Key Takeaways
- Action is measured at the 12th fret and typically ranges from 1.5 to 2.5 millimeters on electric guitars and 2 to 3 millimeters on acoustics.
- Bridge saddle height is the easiest adjustment to make yourself; nut work usually requires a luthier because mistakes are hard to reverse.
- Lowering action requires removing the bridge saddle, sanding it down, and reinstalling it—a process that takes patience and a straightedge.
- Raising action is simpler: you either shim the saddle or replace it with a taller one.
- Always check that your neck is straight before adjusting action, because a bowed neck will make the problem worse no matter what you do to the bridge.
Measuring your current action
Before you adjust anything, measure what you have. Use a ruler or a set of feeler gauges (thin metal strips used to measure gaps). Measure at the 12th fret, which is the middle of the neck. Place the ruler flat across the frets and measure the gap between the bottom of the string and the top of the fret.
Measure all six strings. They should be roughly the same height, though the bass strings (thicker ones) are often slightly higher than the treble strings (thinner ones) to prevent buzz. If one string is much higher or lower than the others, the problem may be a twisted neck or a saddle that needs leveling, not just height adjustment.
Write down your measurements. Most electric guitars sit between 1.5 and 2.5 millimeters at the 12th fret. Acoustics are usually 2 to 3 millimeters. If you are below 1.5 millimeters on an electric and hearing buzz, lowering action further will not help—you need to address the neck or frets.
Checking your neck before you adjust
A straight neck is the foundation of good action. If your neck is bowed forward or backward, adjusting the bridge saddle alone will not fix the problem. Check the neck by sighting down it like a gun barrel: look from the headstock toward the body and see if the frets form a straight line or if there is a dip or hump.
Most guitars have a truss rod inside the neck that controls forward and backward bow. If your neck has a noticeable dip (called relief), the truss rod may need tightening. If it is humped, it may need loosening. Truss rod work is delicate—a quarter turn can make a big difference—and mistakes can crack the neck. If you are unsure, have a luthier check it. Many charge $30 to $50 just to inspect and advise.
Once the neck is straight, you can adjust the bridge saddle with confidence that the change will actually solve the problem.
Lowering action by sanding the saddle
To lower action, you remove the bridge saddle (the small piece of bone or plastic under the strings at the bridge) and sand it down. This is reversible only if you sand slowly and measure often—sand too much and you have to replace the saddle.
First, remove the strings. Loosen the tuning pegs until the strings are slack, then unwind them completely and lift them away. On an acoustic, you may need to remove the bridge pins (small pegs that hold the strings in place). On an electric, the strings usually thread through the bridge or a tailpiece.
Gently remove the saddle. On an acoustic, it usually sits in a slot and lifts straight out. On an electric, it may be glued in place—use a thin, flat tool to pry it out slowly. If it is glued, work from both ends and do not force it, or you may crack the bridge.
Place the saddle on a flat surface (a piece of glass or a granite tile works well) and use 120-grit sandpaper to sand the bottom. Sand in one direction, not back and forth, and check your progress every 30 seconds. Measure the saddle height as you go. Sand only 0.5 to 1 millimeter at a time, then reinstall the saddle and measure the action at the 12th fret. Repeat until you reach your target.
Once the saddle is the right height, reinstall it, thread the strings back through, and tune up slowly. The action will settle slightly as the strings stretch.
Raising action with a shim or replacement saddle
Raising action is simpler than lowering it. You have two options: place a thin shim (a piece of wood or plastic) under the saddle, or replace the saddle with a taller one.
A shim is a temporary fix. Cut a thin piece of hardwood or plastic to fit under the saddle, then reinstall the saddle on top of it. This raises the saddle height by however thick the shim is. You can stack shims if you need more height. The advantage is that you can remove them if you change your mind. The disadvantage is that the shim can shift or compress over time.
A replacement saddle is more permanent. Saddles are inexpensive—usually $5 to $20—and come in different heights. Measure your current saddle and order one that is 1 to 2 millimeters taller. Remove the old saddle the same way you would for sanding, install the new one, and tune up. This is the cleanest solution if you want to raise action significantly.
Adjusting the nut (when to call a professional)
The nut controls action at the headstock end of the neck. If your strings are too high at the first fret but normal at the 12th fret, the nut may be the problem. Nut work is not a beginner job—the nut is glued in place, and removing it risks cracking the headstock. Mistakes are expensive to fix.
A luthier can lower the nut by carefully filing the string slots, or replace it entirely. This usually costs $50 to $150 depending on the guitar and how much work is needed. If you suspect a nut problem, take the guitar to a professional rather than attempting it yourself.
When to stop adjusting and when to seek help
If you have lowered action as far as you can and the strings still buzz, the problem is not action—it is a fret that is lower than the others, a twisted neck, or a bridge that is not seated properly. These are luthier problems. Continuing to sand the saddle will only make the action unplayably low.
If your action is very high and you have raised it further by mistake, or if you have sanded the saddle too thin and it no longer stays in place, a new saddle is the quickest fix. If your neck is visibly bowed or twisted, or if adjusting the truss rod does not straighten it, stop and call a professional. A luthier can assess the neck and advise whether it can be straightened or needs replacement.
Frequently Asked Questions
How much should I sand the saddle each time?
Sand no more than 0.5 to 1 millimeter per session. Reinstall the saddle and measure the action before sanding again. This prevents you from removing too much material and having to replace the saddle.
Can I adjust action on a guitar with a floating bridge?
Yes, but the process is different. Floating bridges (common on archtop and some electric guitars) rest on the guitar body without being glued. You can raise or lower the bridge by adjusting the feet or replacing it with a taller or shorter one. Lowering a floating bridge is easier than sanding a saddle because you can straightforward move the bridge down.
What if my action is different on the bass and treble sides?
This usually means the saddle is not level or the bridge is not seated evenly. Remove the saddle and check that the bridge slot is flat and clean. If the saddle is warped, replace it. If the bridge itself is not flat, that is a luthier job.
How long does it take for action to settle after I adjust it?
New strings stretch and settle over a few days, which can lower action slightly. Expect the action to drop 0.25 to 0.5 millimeters in the first week. Adjust for this by setting action slightly higher than your target when you first install new strings.
Do I need special tools to adjust action?
For saddle work, you need a ruler or feeler gauges, sandpaper, and a flat surface. For truss rod adjustment, you need the correct wrench (usually included with the guitar or available from the manufacturer). For everything else, a professional setup is worth the cost.