Guitar Action: The Complete Guide to String Height & Action Adjustments

When it comes to instruments—especially stringed instruments—one of the most important considerations for the musician is how the instrument plays. In technical parlance, this is commonly referred to as an instrument’s action. Today, we'll be talking all about guitar action—what action is, how to know the right string height for your instrument, and the three ways to adjust the action on your guitar.

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For the piano and other keyboard-based instruments, action simply refers to the feel of the keys under the fingers. For guitar players, the term action can similarly be used to describe the general feel of the instrument when played, but it also has a much more precise definition—the height of the individual strings.

As we'll talk about below, string height plays a critical role not just in the feel of the guitar strings but also in the way that the guitar actually sounds. Finding the right action for you and your instrument is the key to getting your guitar or bass sounding, playing, and feeling the way you want.

A guitar’s action does more than just determine how it plays

A guitar’s action is defined principally in terms of the height at which the strings sit above a given fret. Experts differ in their opinions about which fret is best to measure string height from, with most saying that measuring from between the 8th and the 12th fret, is the best. At Stringjoy, we tend to look at the action at the 12th fret, but if you're more comfortable using a different reference point, that's fine too.

So if action has a more broad definition when referring to other instruments, why is a guitar’s action defined in terms of the height that the strings rest above the fretboard? Well, because this is one of the most principal factors in defining both how the guitar feels and how it sounds. Particularly high-set strings are generally considered by players to be cumbersome and uncomfortable to deal with. On the other hand, setting strings too low results in the dreaded "fret buzz," where the strings vibrate against unplayed frets, resulting in the typical buzzy sound that so many older or poorly maintained guitars are known for.

The height at which the strings sit above the fingerboard is also a critical factor in how aggressively the guitar can be played. Higher string settings will allow for more forceful strumming while maintaining a high degree of clarity and crispness of the notes, while lower settings will tend to quickly generate severe fret buzz when fortissimo passages are called for.

As with almost everything else guitar related, there are significant differences between how the action on electric and acoustic guitars should be set. Here, we’ll take a look at some of the considerations you should keep in mind when setting the action on your guitar and how best to go about it.

Why is guitar action lower on electrics?

The height at which the strings sit above the fingerboard is a critical factor in how aggressively the guitar can be played.

There are significant differences between the way that most acoustic and electric guitars are played. Generally speaking, electric guitars require a less-forceful approach (though depending on the player, this may or may not be the case). Thanks to the invention of the magnetic pickup, a player is able to transmit virtually unlimited sound to an audience with a minimum of physical exertion upon the strings themselves. This is also how so many players can make downright massive sounds with super light guitar strings.

Another consideration with electric guitars is that the amount of perceived fret buzz when the instrument is not plugged into an amplifier can be significant compared to what you will hear under amplification.

Because of all these factors, electric guitar action can be set far lower than that on acoustic guitars, typically anywhere from .15" to .05" lower, on average.

How to choose your string height

In order to measure the height of your guitar’s strings, you should have either a ruler, a feeler gauge, or a specialized string action gauge.

For electric guitar action, in our opinion, a good default string height at the 12th fret is typically about 6/64th of an inch (2.38mm) on the bass side and 4/64th of an inch (1.59mm) on the treble side.

For acoustic guitars, we'll want to go just a bit higher than this:

For acoustic guitars, our recommendation bumps up to 7/64th of an inch (2.78mm) on the bass side and 5/64th of an inch (1.98mm) on the treble side.

These are just rules of thumb, of course. There is a considerable amount of leeway in choosing the right action height, depending on your instrument and playing style. Those who play their guitar strings more forcefully or aggressively may want to raise their strings by a 64th or two whereas those who are able to get away with much lower string heights without producing unwanted fret buzz may find that the lower settings are more comfortable for them.

3 ways to adjust your guitar's action

There are two main ways that the action on a guitar is typically adjusted. These are the adjustment of the truss rod and the bridge saddles. A third contributing factor is the guitar’s nut, which plays a slightly less prominent role in the height of the strings. On electric guitars, none of these means of string-height adjustment are beyond the capabilities of a dedicated do-it-yourselfer who possesses just a couple of tools.

1. Adjusting the truss rod

Most guitars have incorporated truss rods since at least the middle of the 20th century. These are metal rods that run through the neck of the guitar and attach to the body. The truss rod can be loosened or tightened, usually with a simple Allen wrench (if you purchased your guitar new it's likely that it come with one in the case).

The mechanism by which the truss rod affects the string height above the fingerboard is quite simple: loosening the truss rod allows the strings to exert more force, causing a forward-bowing effect, while tightening the truss rod counteracts the strings’ tension, straightening the neck (and of course if over-tightened the truss rod can also cause back-bend in the neck).

Ideally, the truss rod should be tight enough so that the neck of the guitar is ever so slightly bowed concavely. In practical terms, it should appear as if the neck is effectively straight.

As seasons change, so do guitars. It's not uncommon to wake up one day in the spring or fall and find that your guitar has either too high of action or is buzzing due to lower action. When this is the case, a simple truss-rod adjustment (often no more than a quarter turn either way) is all that's required to get everything back into perfect playing shape.

2. Adjusting the bridge or saddle height

The saddle height is the other important factor in determining action height. Depending on the guitar, it can be incredibly easy to adjust, or a royal P.I.T.A...

Broadly speaking, electric guitars tend to either have a "Fender-style" or a "Gibson-style" bridge/saddle system. Fender saddles allow the height of each string to be adjusted individually. This gives the player a great deal of control, but it also means that you will have to pay special attention to maintaining the correct radius so that the action is even across each string. A Gibson-style (Tune-O-Matic) bridge only allows for adjusting either the whole treble side or the whole bass side, which gives you less control, but also makes basic adjustments a bit easier to perform.

On electric guitars, adjusting the saddle height is usually a simple matter of carefully measuring the height and then using a screwdriver or allen wrench (depending on the bridge) to raise the strings appropriately.

Unfortunately, acoustic guitars present a far more challenging situation. In order to raise or lower the saddle on an acoustic guitar, it is necessary to remove the strings, take out the saddle and then either sand it or glue on a shim.

Raising or lowering the saddle on acoustic guitars requires careful, precision craftsmanship and, while many players may be able to complete this job themselves, taking your guitar into a shop and having a professional handle the saddle height adjustment will almost always be worth the usually nominal cost, especially where high-end vintage guitars are concerned.

3. Adjusting nut height

The factors that cause guitar action to shift over time (wear and tear, saddle height shifting, expansion and contraction of wood) tend not to have as substantial of effects on the nut than they do on the bridge or neck. So typically when it comes to regular action adjustments, players can leave the nut as-is.

That said, nuts can wear out over longer periods of time, and this will eventually affect your action after many years. If neither of the above techniques get your action where you want it and it seems like a replacement nut may be required, you can get one that comes pre-cut for not much money, or you can cut one yourself for your preferred gauge of strings.

Go with the guitar action that works for you...

Finding the right action for you and your instrument is the key to getting your guitar or bass sounding, playing, and feeling the way you want.

Because every guitar player has their own unique style, and players’ use profiles differ considerably from one to the other, there are no hard and fast rules about string height, just some general rules of thumb. As with all things guitar, what makes your guitar play the way you want it to is the only thing that matters.

And don't forget, if you're picking up a new set of acoustic guitar strings (or electric), ones that are a different gauge than you're used to, you'll want to consider adjusting the action.