Why Do Guitar Frets Get Smaller up the Neck?

We, guitar players, tend to take our instruments for granted sometimes.

Just as long as things work, what is the point of second-guessing them?

But sometimes curiosity grows stronger than laziness and questions like the one motivating this article arises.

So, why do guitar frets get smaller up the neck?

Guitar fret spacings get smaller the higher you go up the neck, because of how vibrating strings resonate. The shorter a string gets, by being fretted, the higher the frequency at which it resonates, and for that frequency to be a semitone higher, the string’s length must be reduced by around 5.5%.

In this article, I will explain clearly how guitar frets work, and why they need to be arranged in a certain way to produce the pitches they are intended to.

After leaving this page you will have a deeper understanding of your guitar works and will be able to explain it to the uninitiated.

Are you ready to get started?

Let’s go!

Do smaller frets generate higher pitches?

The important thing to define here is that frets are just metal bridges where strings rest to vibrate.

When we talk about bigger or smaller frets we might get confused about, say jumbo vs narrow-thin frets.

These are just different types of fret wires, of different sizes that impact mostly playability and intonation.

More on this topic here:

For this article, when I refer to “smaller frets” I will be meaning the space between frets, or the space between notes, to be more conceptually clear.

Now, getting on the topic: It’s not that smaller fret spacings produce higher pitches, it’s that pitches get closer together as the effective vibrating string gets shorter.

Don’t worry if you didn’t quite get it yet. I’ll explain it further in the next section.

Why do guitar frets shrink the higher they go?

Let’s first review how different pitches are produced on a stringed instrument.

An easy-to-understand example of this is thinking of a harp: It has many strings, and each of them vibrates completely when plucked.

If a harp player wants to play a higher note, he or she picks one of the shorter strings, and the opposite is true for lower pitches.

The thing is, the shorter a string is, the higher the frequency it resonates (or vibrates) when it’s applied enough energy (the player’s pluck).

A longer string will resonate at a lower frequency.

That’s just how physics work, don’t ask too much about it.

Now, think of a guitar: Since the number of strings is limited, in comparison with a harp, the way we have of getting higher or lower pitches, other than the ones from the open strings, is by fretting them.

By fretting a string you are effectively making it shorter.

An open string vibrates from the guitar’s nut to the guitar’s bridge, while a fretted string vibrates from a certain fret to the bridge.

The thing is that guitar frets are designed to generate increasing half-steps in terms of pitch, and for this relationship to be maintained the higher you go, they inevitably need to get closer together.

This is because as strings get shorter, the lengths required for them to resonate at a half-step higher pitch get closer.

There’s a lot of math and calculations involved in determining where frets should be placed on a guitar for all of this to work, but a simplified formula, just to understand how it works is the following:

To get a semitone higher resonating pitch, you need to shorten the length of the effective vibrating string by around 5.5%.

So, now visualize the vibrating length of an open string.

If you want a semitone higher, you should go up 5.5% of its length. Great!

To get a semitone even higher (a tone from the open string) you should now go up 5.5% of the newer effective vibrating length of the string, which is indeed shorter than the open string’s length.

And so on, and so on…

Do all guitar frets shrink at the same rate?

Although the actual calculation for determining the correct spacing of guitar frets is complex, we can argue that all guitar frets shrink at a rather similar rate.

However, keep in mind that we are talking about “rates” here and not absolute values.

The rate would be a percentage of the vibrating string, and not a fixed number of inches or centimeters.

Remember also that there are many different guitar models built with varying scale necks, so even if all of these scales’ frets shrink at the same rate, it won’t mean that fret spacing gets smaller the same amount of inches.

What would happen if all frets were the same size?

If all the spaces between the frets of a guitar were of the same size, you will end up with an instrument that would sound completely out of tune.

Since fret spacing is meticulously designed to provide half-step jumps, by getting smaller as the effective vibrating string shrinks, fixing a certain distance between them will get you just about random pitches across the fretboard that most likely don’t correlate with the traditional occidental tuning system.

It would be a weird sound instrument for sure.

Are frets the only factor that affects intonation?

Fret spacing is probably the most important factor that determines the intonation of a guitar, however, there are many other small things that can affect the quality of the instrument’s tuning.

To name a few:

  • Fret wire size: As you could imagine, the narrower frets are, the more exact intonation gets since the string gets to sit closer to the exact point required for the desired vibration frequency. With thicker frets, notes are fretted easier, but intonation gets a bit messier.
  • String wear: As strings decay, they start to vibrate irregularly across their longitude, thus affecting their intonation.
  • Fretting pressure: Pressing too hard on a fret while playing a note, might get the string to bend slightly behind it, making it effectively shorter, leading to a slightly sharper pitch than intended.
  • Neck relief: When the neck of a guitar recedes and arches a bit, the whole grid of frets gets misaligned, ending up with slightly “wrong” notes.
  • Bridge saddle position: Bridge saddles move up and down, with respect to the string’s length, making it shorter or longer, so an incorrect setup could cause intonation issues.

Does fret wire size also get smaller along the neck?

Fret wire, on most guitars, tends to be the same all along the neck, however, is not unheard of that a manufacturer decides to use a thinner fret wire on the higher frets to improve the instrument’s playability and intonation.

Thinner frets for smaller fret spacings allow more space for the player’s fingers to land and to grip on while reducing the chances of over pressuring the string.