For many guitarists, the idea of adjusting their own truss rod is an intimidating one. After all, there are all sorts of stories floating around out there about players who tried and had not-so-good results. But the resulting improvements in playability, action and overall comfort are more than worth it. So, never fear. In this article, we're going to walk you through the basic steps and give you the knowledge you'll need to—confidently but cautiously—make those minor truss rod adjustments to compensate for the natural shifts in your guitar's neck that happen because of environmental changes, and other such factors.

Table of Contents

Why Should I Adjust My Guitar’s Truss Rod?
What Tools Do I Need to Adjust My Truss Rod?
How Do I Adjust My Truss Rod?
   Check Your Guitar’s Neck for Relief
   Know Your Truss Rod
   Adjust the Truss Rod
      Top Precautions When Adjusting Your Truss Rod
Final Thoughts on Truss Rod Adjustment

Why Should I Adjust My Guitar’s Truss Rod?

One of the things that we love about guitars is that they are like a living, breathing thing that becomes an extension of the player (when everything goes right). A big part of that is because guitars are mostly made of wood. Like almost every organic material, wood responds to its environment by expanding, contracting and shifting with changes in temperature and moisture. Also, over time, whatever volatile oils and compounds remained in the wood after it’s been dried for use in instrument construction evaporate, which changes the nature of how the wood behaves.

Another factor is the constant tension of the strings that are trying to pull your guitar’s headstock toward the bridge. Given enough time, even the lightest gauge strings have an effect. So, the nature of the instrument is that the neck is going to shift away from optimum over time.

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Especially if you live in a place with larger changes in weather over the seasons, your guitar's neck is constantly being tugged on by multiple forces—too dry, the wood shrinks; too wet, the wood swells. As the overall tension on the neck changes, so does your guitar's action. Learning how to adjust your truss rod helps keep your instrument consistently playable, despite these changes. As a side note, we also recommend keeping a proper humidity balance for your guitar by storing it in a case with a humidification system like the Music Nomad HumiReader Humidity & Temperature Monitor or in a humidity-controlled environment.

Before we get into the nitty-gritty of actually adjusting your guitar’s truss rod, there are a couple of questions we frequently get that deserve a quick look.

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First, the techs at the Guitar Center Repairs desk often get asked, “Will adjusting my truss rod lower my action?” As with so many things in life, the answer really is, “It depends.” Action is affected by a lot of things, of which neck relief (that’s what the bow, or lack of bow in your guitar’s neck is called) is only one. Most of the time, it’s not even the main one. That being said, if everything else (neck angle, bridge height and nut height) is correct, yes, getting the right amount of relief in your neck can lower your action. But it’s the final step in that process, not the first one.

Second, we often hear the question, “If I adjust my truss rod, will it stop my strings from buzzing?” Once again, we’re in that “it depends” territory. Like your action being too high, there are a lot of things that can cause string buzzing on a guitar. The three we listed in the last paragraph are factors, plus the possibility of uneven fret height, insufficient string break angle over the nut and/or bridge saddle, and simply having the action set too low (the cycle of raising the action because it’s causing string buzz, then trying to find a way to lower it again can be a vicious one). If you’re getting string buzz and can’t figure out quite why, a trip to Guitar Center Repairs for a setup is probably a good idea. See our article, "What Is a Guitar Setup?", for a list of other benefits from that procedure.

What Tools Do I Need to Adjust My Truss Rod?

Before you get started, let's make sure you have the right tools for the job.

Pictured: Various Tools for Truss Rod Adjudstment

Right from the get-go, we'll say that, if you're interested in doing your own guitar upkeep, it's worth the upfront investment in a full toolkit for guitar maintenance. We recommend the Music Nomad KEEP IT SIMPLE, SETUP Starter Kit Bundle, which has almost everything you'll need in one convenient package. But, if you already have some tools, and just want to get specific ones, you'll need:

1. A truss rod wrench: Usually, your guitar comes with one, if you bought it new. If not, we recommend the Music Nomad Truss Rod Wrench Set, especially if you have more than one guitar.
2. A stainless steel straightedge/ruler and feeler gauge: We recommend the Music Nomad Truss Rod Gauge & String Action Gauge Combo Bundle which, together, have a number of features you'll need to get that truss rod properly adjusted.
3. A capo: What? You don't already have one? In that case, our recommendation is the top-rated D'Addario NS Tri-Action Capo. You get the dual benefit of having a useful tool and being able to play "Wonderwall" any time you want.

Okay, got your tools? Then let's get that truss rod adjusted.

How Do I Adjust My Guitar’s Truss Rod?

The first thing you'll need to do is set up your work surface. You'll want to have a well-lit, flat surface that's big enough to lay your guitar down on, with easy access to the neck and the truss rod adjustment nut. You'll also want to put down a clean cloth or neoprene pad to protect the back of your instrument and a neck support like the Music Nomad Cradle Cube to support the neck at the headstock.

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You'll also want to set aside some time to make your adjustments. Neck relief doesn't change instantly, so you'll want to have enough time to wait 10 or 15 minutes between adjustments to let the neck settle into its new resting tension.

Check Your Guitar’s Neck for Relief

First, we'll check to see what kind of relief (how much bow is in the neck) you currently have and whether it's positive (curved up) or negative (curved down). Generally speaking, you don't want an absolutely flat neck—especially if you prefer lower action—as that can lead to fret buzz. The neck needs to have some slight positive relief to play properly. So, here's what you do:

1. Tune your guitar to pitch.
2. Place the capo at the first fret.
3. Fret the low E string at the 17th fret.
4. Use the feeler gauge or the action gauge markings on the straightedge to measure the distance between the string and the fret at the 8th or 9th fret. What you want to see is a measurement of .010–.012" (that's .25–.30 mm, if you do metric). If that's what you get for a measurement, you're pretty much done. Your truss rod doesn't really need any adjustment, and you can put the tools away and go play.

Pictured: Checking String Height at the 8th Fret

If, however, the gap is larger or smaller than that, write down that number for reference. Then, it's time to make some adjustments.

Know Your Truss Rod

It's important to know what kind of truss rod you're dealing with in your guitar, which should be easy enough to find on the manufacturer's website or elsewhere on the net. There are two principal types of adjustable truss rod in use today: single action and double action.

A single-action truss rod is laid into a curved cutout that establishes the maximum positive relief for the neck. In fact, the wood of the neck is an integral part of the tension. Tightening a single-action rod can only remove positive relief, by creating more back bow (curving the neck backward). It can never create more positive relief than what the guitar has when the truss rod is at maximum looseness. This does mean that, if your neck is measuring as having too little positive relief and the truss rod nut is already loose, you need to take that guitar to your local Guitar Center Repairs location, where we can help you figure out what might need to be done.

Pictured: Truss Rod Access on a Gibson Les Paul

A double-action truss rod operates independently of the inherent tension of the wood in the neck. This means it can be adjusted for both positive and negative relief. It's in many ways a more flexible solution (see what we did there?), but the trade-off is that, because there are two rods instead of one, the double-action truss rod is somewhat heavier than a single-action rod.

Oh yeah—before you start, it's kind of important to know where your truss rod adjustment nut is located. It's usually at the headstock on electric guitars—either under a truss rod cover that's attached with a wood screw or two, or a "bullet"-style nut just peeking out from under the fingerboard. Some modern bolt-on necks have a side adjustment down by the neck/body joint. On an acoustic, it's either inside the sound hole in the neck block, or at the headstock. 

Adjust the Truss Rod

Before you actually apply the wrench to the truss rod nut, we need to consider a few things to avoid potential problems. The nature of truss rod adjustments are that they should be relatively fine adjustments—no more than a quarter of a turn at a time, and frequently less than that. Since the wood in the neck needs a little time to come back into balance with the new truss rod tension, adjustments that are too large can over torque the nut and break it or the rod itself, because it's trying to do too much all at once. That would change this from a minor adjustment to the need for major surgery on your neck. We're not trying to scare you off from making your own truss rod adjustment here—just making sure that you have the proper perspective and don't rush things so the results are what you intend them to be.

Pictured: Using a Capo while Checking Neck Relief

Top Precautions When Adjusting Your Truss Rod

1. Only use the proper size adjustment tool/wrench: "Close enough" isn't right here, as a tool that doesn't fit can strip out the nut. This not only keeps you from making the adjustment, but replacing the truss rod nut is also not a repair that you want to have to pay for.
2. Know where your starting point is: If you don't know where you started, you can't tell how far you've gone. It's a good idea to make a small alignment mark with an erasable marker or pencil on the wood and on the nut so you can more easily keep track of how much you've adjusted things.
3. When making adjustments, "gentle" is the word: Any sideways torque on the adjustment nut can bend the rod (not in a good way) or potentially break the nut. It's a good idea to always start by loosening the nut a quarter turn, then bringing it back to its original position before you make your first adjustment.
4. Adjust in small increments: You don't ever want to turn the truss rod nut more than a quarter turn at a time. A truss rod may be made of steel, but it can still break when too much stress is applied too quickly. Also, you need to give the wood time to gradually adjust to the "new normal."

So, we're finally ready to start adjusting the truss rod. Or are we? Which way do you need to turn it? Do you need to tighten it or loosen it? Time to refer back to the measurement you got when you checked your neck relief (we told you to jot it down somewhere). The general target is .010"/.25 mm. If your measurement was higher than that, you've got too much positive relief. If it was less than that, you've got too much back bow (negative relief). Since the ideal state of a neck is to have just a small amount of positive relief, let's think of the truss rod, even a double-action one, as an adjustment in negative relief and map that to the old "righty-tighty/lefty-loosey" rule. In this case, "righty" increases negative relief by tightening the truss rod, and "lefty" decreases negative relief by loosening it.

Pictured: Measuring for Neck Relief

So, now we that know where we are, where we need to go and which direction to turn things to get them headed in that direction, it's time to commence with the tweakage. Remember that we're doing small adjustments here and giving the neck time to settle. Here's the order of operations:

• Loosen your strings—they just need to be slack enough that the tension is taken off the neck.
• Locate your truss rod nut and make the alignment mark, as noted above.
• Loosen the truss rod nut a quarter turn and bring it back to its original position to make sure that everything is moving the way it should.
• Make your first adjustment of no more than a quarter turn is in whatever direction you determined you need—tighter for more back bow, looser for less.
• Tune strings back to pitch and give the instrument a little time for the neck to settle into its new alignment. 10–15 minutes is good, and you can use that time to get in a little practice, since playing the guitar will help this process along.
• Go back to the "Check for Relief" section above and, uh, check for relief. If it's not where you want it yet, repeat the last three steps (plus the “loosen your strings before making an adjustment” bit) until it is.

Final Thoughts on Truss Rod Adjustment

That's it. While it may take a little time if the initial adjustment you need is larger, it's really pretty simple, now that you understand what you're doing and why. A quick note: If you find it getting hard to tighten the truss rod nut and still aren't getting sufficient back bow to correct the problem, or, if you've loosened it all the way and aren't getting enough positive relief, you might want to consider having a professional check it out. Drop by your local Guitar Center store and talk to the folks at the Guitar Center Repairs desk. They'll be glad to help you out.