The function of the guitar radius

A precious piece differs from a great musical instrument only in small details: as a musician, you have to do a lot of experience and you must try all the technical variations and all the materials that make up a guitar to fully understand which settings make precious your style.

The good guitarist must know all the individual details of his instrument and the guitar neck is definitely one of the fundamental parts of it: the harmonic case amplifies the sound but this comes from the various elements that hold the strings in tension and from the strings themselves.

The neck is made up of various parts, and the fretboard is certainly one of the most important. A fundamental detail that can affect a musician’s style and his comfort during the performance is the guitar radius.

What the guitar radius is

The guitar radius is the measure of the fretboard curvature radius of the acoustic guitar neck; that differs from the classical one that has a flat fretboard.

The radius measurement, expressed in inches, is the ray of the hypothetical circumference that coincides with the fretboard curvature.

Both the upper part of the neck and the frets have the same curvature, which usually varies according to the manufacturer of the instrument or according to the instrument type.


Some guitar radius measures are widespread because they have been adopted by the various manufacturers and they are considered almost as standards: the 7.25” of the Vintage Fender Stratocaster; the 9.5” of the Modern Fender Stratocaster; the 10” used by Gibson; the 12” we found in Gibson and Ibanez and the 16” of the Jackson models.

However, it is not unusual to meet fretboards with a different radius, ranging from intermediate values up to 24”, which indicate a fretboard with almost no curvature.

An important aspect is that the neck curve must be followed by the guitar bridge saddles and that also the pickup poles must be at the right height; if you want to change the fretboard by choosing one with a different radius it is advisable to adjust them.

It’s best to delegate this kind of operations to an expert luthier otherwise it is better you choose a guitar that already has the fretboard curvature you want.

The importance of guitar radius

Guitar radius is one of the guitar neck elements that determine the playability of the instrument and the comfort of the artist.

For a musician to move in an easy way his own hand, to articulate the chords, by pressing on the strings is a fundamental variable considering that, in addition to the precision in the execution, a good resistance is necessary: both a drill and a concert can last several hours.

Obviously you should make the considerations on the instrument type and on the most suitable features according to your needs and aspirations: choosing a bike you would choose its measure to be comfortable, but you would not take a city model to make races and vice versa you would not use a racing bike to move around the city.

A guitar with a lower radius will allow you to play chords with ease, arpeggios at the first key and will make it easier the use of the barré.

By orienting your choice on a greater radius, which involves a flatter fretboard, you will have a lower action and you will be facilitated in the solo playing at the last key and in the bending.

During bending, in fact, the action of the neck curve causes a lower string height.

Obviously, guitar radius is not the only factor that improves the instrument usability but should be well regulated both the action and the strings curvature, which must follow the neck curve.

The compound radius

There are some acoustic guitar models that have a particular neck type whose fretboard has a radius of different sizes: the so-called compound radius.

The compound fretboard was designed by Warmoth brothers. In its traditional version it starts with a 10 inches radius at the height of the nut, then it gradually flattens up to 16 inches at the fretboard end. However, there are also other guitar models with minor or greater differences between their radius measures near the headstock and at the harmonic case.

The advantages of choosing a compound radius guitar are to be able to obtain both a better positioning for the chords on the first frets and a wider use of bending at the bottom of the neck, still having a regular action: this fretboard is flatter in the middle and this causes a more regular action so the string can best resonate with a bending capable of 2 and a half tonnes of excursion without stoppages.

The radius compound, therefore, gives the instrument a better playability.

But the fretboard curvature radius is just one of the aspects that can be customized to get the sound and the level of usability that you prefer: the entire structure of the acoustic guitar neck allows you to customize your instrument.

[Photo credits: Freebird, Warmoth]