DEEP THOUGHTS

Decoding "Good Action"

Oct 10, 2025 • Dan Holtz, Lakeside Guitar

I'm Bad (You Know It)

We've all experienced the affliction known as "bad action" on a guitar or bass. Yet, I would argue that most players struggle to define it. What's bad about it? Sometimes we think we know, "It's really high around the upper frets." Or, "it just doesn't feel smooth anymore, I feel like I'm fighting it."

As it turns out, this is because "bad action" ain't just one thing. It's a collection of potential ailments that get diagnosed as a single condition. Bad action can show up in different ways, and sometimes with comorbidity, complicating your understanding of the problem.

Stairway to Heaven

When your strings are rising steadily towards the heavens as they ascend into the 12+ fret zone, you are experiencing the most common action issue: a long ramp. Unfortunately, there are a few different reasons this could be happening.

The most obvious suspect is the saddle(s) – too high. Electric guitars make it easy enough to adjust saddle heights, but acoustic guitars are not user-friendly for this adjustment. In either case, you have to be able to measure your work down to the 64th of an inch. If your electric guitar has a tremolo bridge (also called a "floating" bridge), this could be complicating the problem. String tension fighting spring tension creates a lot of headaches.

If it's an acoustic guitar, there are two much more serious problems to check. First is neck alignment. Run a long ruler (18" is good) down the frets from the middle of the neck to the bridge. Where does the bottom tip of the ruler fall? If it's flush to the top of the bridge or really close, good. If not... well... yikes!

The other thing to check is what's called "bellying". Lay the edge of the ruler on the body just below the bridge, from side to side. Does it rock back and forth like a seesaw? If it's a little bit, it might normal and ok. But if it's a bunch, and you can see the bridge tipping forward, or worse, coming away from the body... well... again, yikes! 

Electric Slide

There's also a short ramp. A little more subtle to detect, but super common in acoustic guitars. Imagine looking down at the low E string while you're playing. It looks too high. But then turn the guitar "lefty" and look at the high e string... it might look pretty low and tight.

You can self diagnose this pretty easily. Start by looking down the neck toward the bridge. Check out where the bottom of the strings meet the top of the saddle(s). Do the string heights appear to descend as they approach the high "e" string? Then, look up the neck at the nut, do you see it there? The nut can be a little tougher to spy. I have no idea why guitars get setup this way, because it's not fun to play.

Bad to the Bone

Less common, but notable, is a bad cut on your nut. Those little slots are cut by hand with little, specialized files. I know, I have 3 sets of 'em, and they are stupid expensive. Anyway..

You naturally experience much higher tension on the string as it nears termination. Any increase in string height at the nut results in significant increase to the force required to make it sound out clearly. In other words, when slots are cut too high, it can be a real drag to play in the lower frets. Open chords will really build up them callouses. On the flip side, if you cut 'em too low, you get buzzy strings.

It's Lump!

I like to describe this kind of bad action as "lumpy" because that's how it feels. It's also "stealth" bad action – it can look like good action, but it feels like bad action. Strats often arrive in this condition, but other guitars, too.

At the nut, it's nice and tight. Up higher, fret 12 or 17 (acoustic vs. electric), it looks pretty lean and mean. Yet, something is not right. It just doesn't play well. This is the stealth bad action, and it's usually caused by an inferior setup.

Here's what's probably happening. Someone attempted to improve the action, but the true issue was not properly addressed. Maybe the nut slots were cut too low. Maybe someone set the saddle to low. Or maybe, there are some uneven frets. None of that was considered. Instead, the intrepid "truss rod ranger" came to the rescue, with allen wrench or nut-driver in hand!

Look, we are led to believe that the truss rod is a magical piece of equipment that can be mysteriously adjusted to solve any manner of playability issue. Not true, but the myth persists. The truss rod has just one, single purpose: to true the neck as close to straight as possible. Any amount of back bend in the neck is called "relief", in that it's relieving string tension. This is not to be confused with bowing, when the neck bends upward. That's never acceptable.

In any case, when the truss rod is allowing too much relief (i.e. back bend in the neck) you get this deep zone in the middle of the neck where the action feels really spongy. Furthermore, it divides the guitar into 3 zones with the bad action right in the middle. That "lumpiness" as you move up and down neck is very distracting and degrades the playing experience.

How Sweet It Is

Here's my proposal to you: good action on a stringed instrument is when it feels as close as possible to the same everywhere on the neck. When your fingers don't have to adjust to different amounts of string tension (i.e. pressure required to press them down) you stop thinking about the guitar, and you start thinking about the music.

In order to achieve this effect (and yes, it is just an effect), you have to take into consideration the physics of a metal wire being stretched and then bridged across two points. Your fretting hand is playing from one termination point (i.e. the nut, and the highest tension) to the middle (i.e. the 12th fret, and the lowest tension) and maybe a bit beyond middle.

If the string height were literally the same everywhere, it would not feel even. The strings must be lower at the termination point (i.e. the nut) to accomodate for higher tension, and higher in the middle (12th fret) to accomodate for lower tension. The question is, how much?

Additionally, there's the cylinder effect. Look up the neck at the edge of your fingerboard, where the radius is very visible Strats are often 7.25"-9.5", Martins are usually 12"-15". What does this mean? Imagine continueing to draw an entire circle from the radius of your neck. If you do, the resulting circle from a Strat would be 9.5" diameter (or 7.25" if it's got a vintage style neck). This is a rounder neck. Higher numbers are flatter necks.

OK, now imagine a cylinder with a ruler laid lengthwise across it, end-to-end. It's making contact with the cylinder everywhere. Now, turn the ruler slightly. Now it's not making contact at the ends. It see-saws on the curvature of the cylinder.

Your strings are experiencing the same effect. Why? Because your neck is wider at the bottom than at the top. The strings are crossing the middle of the round. This complicates things because it means that the middle of the guitar is actually higher relative to each string, especially the outer strings.

This is where truss rod relief comes in! More dramatic radii (lower numbers) require more relief in the neck. So, like a Strat might need .007"-.010" in neck relief, whereas a Martin might need only .003"-.005". Seems like a tiny difference, but in luthier-land, that's a big difference.

So, you have to balance the heights of the termination points (i.e. nut and bridge) with the relative center-height of the guitar (i.e. the truss rod) to achieve this effect of even playability and tension everywhere. In other words, you have to create a long ramp – but at a strictly controlled angle.

Finally, but not to be dismissed, you should avoid (at all costs) the short ramp. Every string should be the same distance from the fretboard from bass to treble. Again, this has to do with the fingerboard radius. If the nut slots were cut flat across, the middle strings would be closer to the fingerboard than the outer strings. More often, as above, the bass strings are set higher than the treble strings. IMHO there is zero reason for this. No short ramps!

A Little Less Talk (A Little More Action)

Now that you have some familiarity with the four horseman of bad action, and some physics and philosophy around good action, let's get specific. There is a sweet spot – it's not hypothetical, nor is it mysterious. Amazingly, it's the same for pretty much all guitars and basses – both electric and acoustic.

This golden ratio is a simple formula, but in practice it can be more aspirational than achievable. Small variations are often necessary due to the unique limitations of any given instrument. Wooden instruments change with moisture conditions, heat, time and the amount of play they have absorbed. I always aim for the same constants, and I adjust to maximize what any given instrument is capable of.

OK, so I'll shut up and give you my formula. It's pretty much the same for every guitar and bass, with adjustments in either direction based on the unique conditions of that instrument.

Golden ratio (1:4):

• .005" truss rod relief

• .020" @ first fret

• .080" @ 12 fret (or 17th fret for electrics)

• Frets need to be level!

Finally, it really is worth the money to let me do it for you. It requires specialized tools, and it helps if you do setups all the time. I see (and fix) a lot of bad setups. But, if you have the tools (and the courage), these numbers will get you darn close.