You might have noticed that on a good number of electric guitar and basses, their fretboards (also known as fingerboards) aren’t exactly flat. Most of them have a slight convex curve through their width. This is known as their fretboard radius, the measure of the arc of the fretboard across its width. In this article, we dig deeper into how this spec is measured along with some examples from popular guitars.
The measurement of the fretboard radius refers to the radius of a circle from which a small segment of the circumference equal to the width of the fretboard is taken. For example, if you have a circle with a 7.25” radius and remove a piece of its side equal to the width of a fretboard, you have a 7.25” fretboard radius. If you take the same width from a circle with a larger radius, you’ll end up with a slightly flatter radius. The higher the measurement, the flatter the curve, and vice versa.[caption id="attachment_2515" align="alignnone" width="447"] The measurement of the fretboard radius refers to the radius of a circle from which a small segment of the circumference equal to the width of the fretboard is taken. The lower the radius measurement, the greater the curvature on the neck.[/caption]
Fretboard radius is responsible for a neck’s certain feel, made to give it a certain character of playability and comfort. It’s a subjective measurement though; there’s really no right or wrong degree of it but there have been several established measurements that players can choose from to suit their personal preferences. A smaller, more curved radius is generally thought of as being more comfortable for playing chords. Meanwhile, a larger, less curved radius is generally considered to be better suited for single notes and bending.
The radius specs vary not only from manufacturer to manufacturer but often among each of their own electric guitars and basses as well. Fender, for example, tends to produce most of their electric instruments with either a 9.5” radius, found on about two-thirds of their modern guitars, or 7.25”, a vintage-era measurement used for most of their electrics from the 1950s up until the 1980s. The infamous Gibson Les Paul on the other hand usually comes with a 12” fretboard.
There are also several instruments that feature a compound-radius design. In these designs, the amount of curvature gradually changes across the length of the neck, with the arc greatest near the headstock and steadily – but not completely – flattening toward the body-end of the fretboard. Newer models of Jackson guitars tend to feature compound-radius fretboards, a common measurement being 16” at the body-end and 12” near the headstock. The benefit of this design is that some players find the rounder profile near the headstock preferable for chording and the flatter profile near the body-end preferable for soloing.