The specifications for any acoustic guitar include its “scale length.” In theory, scale length is the length of the freely vibrating section of any open string on the guitar—that is, the length from the nut to the saddle (specifically, the bridge mounted within the saddle). Guitars that have a scale length toward the upper end of the spectrum of common lengths are called long-scale guitars, while those toward the lower end of the spectrum are called short-scale guitars.
This article continues the series with useful information about modern acoustic guitars. You can see the previous posts there:
How Scale Length is Measured, and Why It Is Not Measured As You Would Expect
Basic physic principles of wavelength and frequency dictate that the 12th fret of a guitar, which marks a pitch one octave above the open-string note, falls at the halfway point of the free-vibrating section of the spring. Therefore, the standard method to determine a guitar’s scale length is to measure the string from the point where the nut meets the fretboard to the center of the 12th fret, and then double the result.
The reason that they don’t just measure the entire vibrating section of the string, from nut to bridge/saddle, becomes clear if you look carefully at the saddle of any acoustic guitar. The bridge will be slightly slanted, so that the vibrating length of one string differs from that of another. This adjustment is necessary to preserve intonation across the instrument, due to the variations in string weight and tension, and the fact that the neck will inevitably bow slightly more on the bass side of the fretboard than on the treble side. That is why scale length only represents the length of the free-vibrating section of the strings in theory. In practice, if you laser measure any string on any guitar, the result will differ slightly from the guitar’s specified scale length.
NOTE: Scale length is not related to fret count!
Many guitarists mistakenly associate scale length with the number of frets on an acoustic guitar. One specification has nothing to do with the other. Lengthening the vibrating portion of a guitar’s strings does not mean that more frets can be added, because the spaces between frets represent a certain percentage of the string’s vibrating length. A shorter scale length does not indicate fewer frets, just frets that are closer together.
Common Scale Lengths of Steel String Acoustic Guitars
The table below shows some of the standard scale lengths used by major steel string acoustic guitar manufacturers. The correspondence between National guitars and the guitars of Paul Reed Smith is no coincidence: Smith specifically designed his instruments to have a similar feel to classic steel guitars.
|Martin||Dreadnought series (D18, D28, etc.)||25.4” (645mm)|
|Martin||Short scale “0” series (0, 00, 000)||24.9” (632mm)|
|Martin||Little Martin travel series||23” (584mm)|
|Gibson||Most modern acoustics (J-45 Legend, etc.)||24.625–24.75” (625–629mm)|
|Gibson||Jumbo series||25.3–25.5” (642–648mm)|
|Guild||Standard neck||24.75” (629mm)|
|National||Standard models (steel body)||25” (635mm)|
|Paul Reed Smith||Standard models||25” (635mm)|
|Seagull||S-6 and other standard models||25.5” (648mm)|
Common Scale Lengths of Classical Guitars
Overall, classical guitars have longer scales than steel string guitars. Players specializing in purely classical technique value wide fret spacing, as it enhances the effect of traditional vibrato. A vintage classical guitar will generally have a scale length of 660mm—a whopping 26 inches, longer than any common steel string guitar.
There are current manufacturers whose specifications indicate a 660mm scale length, although many of them “cheat it” just a little to make their instruments feel more playable to modern players. For example, most Bruce Thompson Classical Guitars are long-scale instruments, listed as having a 660mm scale length on the company’s website. However, the official specs list the scale length as 656mm (25.8”).
Short-scale classical guitars generally come in at 650mm (25.6”), and at that, are still longer than the vast majority of steel string acoustic instruments. Maker Roger Williams, for example, offers a 650mm scale length as his standard neck, but also offers a 640mm (25.2”) alternative for all models. Note that 640mm is well within the normal spectrum of scale lengths for steel string guitars, so these instruments feel very comfortable to players who are not classical specialists.
Scale Lengths of Crossover Guitars
Speaking of guitarists who do not specialize, “crossover guitars,” which have nylon strings but are similar in size and design to steel string instruments, are increasingly popular. Not surprisingly, such guitars tend to have shorter scale lengths than their classical cousins. Guitars in the Hill Guitar Company’s Torres crossover series, for instance, are available in 640mm (25.2”) and 630mm (24.8”) lengths.
Does Scale Length Really Matter?
As explained above, the most immediately noticeable aspect of scale length is that it affects fret spacing. A player with shorter, narrower fingers will tend to find short-scale guitars more comfortable, whereas one with long and/or thick fingers will often prefer the wider fret spacing of a long-scale instrument.
In the realm of electric guitars, especially solid body instruments, scale length has a significant effect on an instrument’s timbre. A longer vibrating section of each string means that the strings have higher tension. The result is a crisper, clearer, brighter (and some would say thinner) tone. That is why a Fender Telecaster (25.5” scale length) has very clean, clear bass tones and stinging treble, while a Gibson Les Paul (24.75”) is known for warm, full tone but some muddiness at the low end.
Theoretically, the same principles would apply to acoustic guitars. However, the tone of acoustic instruments is affected by so many other factors—the type of wood used, trueness of the grain, nature of the bracing, 2-piece vs. 3-piece back, etc.—that scale length is a very minor influence on their overall sound. A mahogany guitar with an ultra-short scale length will still sound crisper than a long-scale rosewood dreadnought. For acoustic players, scale length is above all a matter of comfort and personal preference.