In terms of the size and shape of the instrument, it is largely true that a cello is a cello, a soprano flute is a soprano flute, and a tenor sax is a tenor sax. Steel-string acoustic guitars, however, come in a vast array of body types. Just as every incarnation of the human form makes a unique contribution to the beauty of our species, each of the various guitar sizes and shapes highlights one or more of the many sonic elements that make the acoustic guitar so beloved all over the world.
Making sense of all those different conceptions of what a steel-string guitar can and should be, however, can be overwhelming. I have often heard inexperienced players cry out in frustration at guitar shops as a sales representative peppers them with questions about whether they prefer a parlor, dreadnought, jumbo, or auditorium instrument. “I just want a regular acoustic guitar!” the young player will angrily protest. The problem is that there is no such thing—since the earliest days of the steel-string “folk” guitar, makers have experimented with different shapes and sizes.
At the end of this article, courtesy of the C.F. Martin Company, you will find detailed information on the dimensions of many of the most popular steel-string guitar body designs. In order for that data to be of any use to you, however, we should first delve into the most fundamental question about guitar shape and size: What difference does it make?
Not Just How Much You Got, But Where You Got It: 12-Fret vs. 14-Fret Guitars
The first major distinction between one acoustic guitar and another is whether the body joins that neck near the 12th fret or the 14th fret. Most smaller steel-string guitars come in both 12-fret and a 14-fret varieties, and several makers produce 12-fret versions of the typically 14-fret larger sizes as well.
Simple geometry will tell you that among guitars of the same body style, 12-fret models will tend to have larger air chambers than 14-fret versions. Note, however, that the added space for reverberation is in the immediate vicinity of one of the least resonant parts of the instrument: on the neck side of the sound hole, where the different woods of the neck, top and sides of the guitar are all joined.
This paradox has a peculiar effect on the guitar’s sound, often described as “hollowness.” Hollowness should not be mistaken for thinness—many 12-fret guitars have beautifully full tone. I would describe hollowness as a slight bumping up of the volume of the principal pitch being played, without any corresponding amplification of its accompanying overtones. The resulting clarity of pitch can be great for fingerpicking, but less desirable for strumming and single-string playing because there is less “zing.”
The Shape Everybody Knows: Dreadnoughts
As far as we know, C.F. Martin himself fashioned the first dreadnought steel-string guitar (at a minimum, he gave us the name), and the body shape has been the dominant acoustic guitar design ever since. Ask someone to close their eyes and picture an acoustic guitar, and unless they have direct experience with another design, odds are that they will picture a dreadnought. (Of course, if you ask the same person to pick out the dreadnought, or “normal” guitar, from a wall of acoustic guitars at the music store, the results would be decidedly less predictable!)
Dreadnoughts have large bodies—too large for many young or small-framed players, really—and gentle curves. They are generally known as “do-it-all” instruments, perhaps not the absolutely perfect instrument for any one specific style of playing, but ranking in the top three among acoustic guitar options for almost every style. Strummed, they produce ringing chords with remarkable sustain. Fingerpicked, they are resonant but clear.
The common view is that dreadnoughts, especially those made of deeply resonant rosewood, favor bass over treble. Martin’s own booming D-28, beloved by bluegrass players, certainly lends support to that opinion. However, the specific design features of a dreadnought greatly influence its low-high balance. Martin’s HD-28, with its scalloped braces, and D-35, with its three-piece back, for example, are tremendously versatile due to their beautiful evenness across all registers.
Almost every major acoustic guitar maker produces multiple dreadnought models.
Gibson’s Variation: The Round-Shoulder Dreadnought
Imagine a large dreadnought sucking in its waist a little to impress an attractive passerby, and you have pictured a round-shoulder dreadnought. The design is the brainchild of Gibson, and although many manufacturers now produce round-shoulder dreadnought models, the “workhorse” Gibson J-45 is almost the beginning and end of any discussion of this shape. Similar in many ways to a standard dreadnought, the J-45 is prized for its particularly well defined mid range.
Big Made Bigger: Jumbos
If you have ever noticed that an eight-person cello section in an orchestra can easily match the combined volume of 25 violinists, then you certainly know that in general, bigger sound chambers produce bigger sound. Beginning with Gibson’s first models in the mid-1930s, jumbo acoustics have been designed with that idea in mind. With a very rounded bottom end of the body and a much more “girdled” waist than a dreadnought, a jumbo guitar can be unwieldy, but it is volume-pumping powerhouse.
To this day, all of the best-known jumbos are Gibsons, although many guitar makers, including rival Martin (J series), offer jumbo models. The most popular model remains the Gibson J200 or SJ200. The SJ stands for “super jumbo,” but the name difference is actually just an indicator of the time period during which the instrument was made, since Gibson’s nomenclature went through a number of changes during the 20th century.
Within the Gibson line, many guitars are designated as “advanced jumbos,” a moniker Gibson historically employed pretty much any time its designers made what they believed to be an improvement over earlier models, from a new combination of woods to the creation of a thinner, “faster” neck.
Because of their deeply resonant bass and overall volume, jumbos (including the affordable Epiphone EJ200) are much sought after by rhythm strummers, especially those who accompany soloists. However, their treble range is no less substantial and is beautifully resonant, well suited to single-string and traditional blues playing. A blues player I know always says that the first time he played Robert Johnson’s “I Believe I’ll Dust My Broom” on a J200, it sounded like someone was sitting two feet in front of him, facing him and playing along. He simply couldn’t believe that one guitar could belt out that much sound.
Small Is Beautiful: Parlor Guitars
Historically, steel-string parlor guitars represented the opposite end of the size spectrum from jumbos. Today, the small end of the guitar size spectrum is a much murkier zone, thanks to the introduction of the Martin Backpacker and Little Martin models, Yamaha’s Mini acoustic, and “baby” guitars made by Gibson and others. Nevertheless, parlor guitars remain the smallest steel-string acoustics with a long history of mainstream use. As the name suggests, these instruments were traditionally seen as best suited for use in small spaces with small audiences.
In reality, the instruments that we call parlor guitars today were “regular” acoustic guitars prior to the latter 1800s, when the increasing use of steel-string guitars in multi-instrument ensembles drove the demand to boost their volume. As a result of that demand, parlor guitars took a distant backseat to dreadnoughts and jumbos in sales and popularity throughout most of the 20th century. Thanks to improved electronics and amplification, however, parlor guitars have enjoyed a spectacular renaissance over the last 30 years, outselling their larger cousins in many guitar shops.
Classic examples of parlor guitars include Martin’s 0 and 00 series. Lovely recent additions to the family include the Farida M-2E electro-acoustic and the affordable G9515 Jim Dandy Flat Top by Gretsch. As with dreadnoughts, almost every major guitar maker offers at least one parlor model.
Apart from the obvious appeal of their portability, parlor guitars offer beautifully clear tone and a quiet but subtle richness that rewards those willing to “dig in with their ears.” Certainly, they cannot match the dreadnoughts and jumbos for sheer volume and overall resonance, but they are beloved by precise fingerpickers and folk traditionalists as well as indie-alt artists who favor stripped-down simplicity. Furthermore, because they have short scale lengths, parlor guitars have lower string tension than long-scale guitars and are thus very well-suited to string bending and blues-style vibrato (rapid micro-bending).
Mid-Sized Miracles: Auditorium and Grand Auditorium Models
Comfortably positioned at the center of the steel-string acoustic guitar size and shape spectrum are the auditorium and grand auditorium (also called “concert”) styles. As you would expect, the grand auditorium is the larger of the two, but since the dividing line between them is somewhat blurry, we will look at both types together.
It should almost go without saying that these guitars offer some of the advantages of parlor instruments and some of the advantages of the big boys and girls, while (at least in the eyes and ears of some) minimizing the disadvantages of both. Many guitar buffs have proclaimed them the “jack of all trades” guitars of the 21st century. It is worth noting that grand auditorium guitars match many dreadnoughts in total length, and often in scale length as well. Therefore, they are significantly smaller than dreadnoughts and jumbos only in body size.
The classic (and original) example of auditorium guitars is the Martin 000 series, complemented today by the same maker’s OM line. Auditorium guitars are not as universally produced by guitar manufacturers as dreadnought and parlor styles, but numerous makers offer at least one model. The manageably sized body and deep curve at the waist of auditorium instruments is beloved by advanced fingerpickers and others who simply love the feel of an instrument that rests on the knee as if it was born there.
Martin also produces grand auditorium guitars—the Grand Performance, 0000, and M series—but there is no doubt that the driving force behind the rise of this middle-of-the-road instrument has been Martin’s chief rival since 1974, the Taylor Guitar Company. Taylor pioneered the grand auditorium size and offers numerous models—the 214 DLX, the 224ce, and the 414ceR, to name just a few. (For Taylor guitars, the “ce” indicates a cutaway body.) True to her name and the giant arenas where she performs, Taylor Swift plays Taylor grand auditorium acoustics; suffice it to say, that has not slowed the rapid growth in the popularity of this versatile guitar size.
Acoustic guitar dabbler Fender has also put forth some very respectable grand auditorium guitars, such as the FA135CE.
The Numbers: Specifications for Popular Acoustic Guitar Shapes/Sizes
As promised, the table below, showing data obtained courtesy of C.F. Martin & Co., gives the dimensions of Martin guitars of all shape and size categories. Although these measurements are not universal, any guitar that falls into a category included in the table will have very similar dimensions to those shown, regardless of the manufacturer.
Martin Six-String Acoustic Guitar Dimensions
|Guitar Type / Model||Total Length||Body Length||Body Width||Body Depth|
|0||37 3/4"||19 1/8"||13 1/2"||4 1/16"|
|00||37 3/4"||19 5/8"||14 1/8"||4 1/16"|
|000 or OM||39 5/8"||20 9/16"||15"||4 1/8"|
|D||37 7/8"||21"||15 5/5"||4 7/8"|
|0 Tenor||35 1/4"||17 1/8"||13 9/16"||4"|
|00 Thin Body||38 5/8"||18 7/8"||14 5/16"||3 1/4"|
|00||38 5/8"||18 7/8"||14 5/16"||4 1/8"|
|00 Deep Body||38 5/8"||18 7/8"||14 5/16"||4 5/8"|
|00 Sloped Shoulder||39 9/16"||19 7/16"||14 3/4"||4 1/8"|
|000 or OM||39 13/16"||19 3/8"||15"||4 1/8"|
|14-Fret Grand Auditorium/Concert|
|Grand Performance||40 3/8"||19 3/4"||15 3/4"||4 1/2"|
|0000 or M||40 5/8"||20 1/8"||16"||4 1/8"|
|D||40 1/2"||20"||15 5/8"||4 7/8"|
|D Jr.||37 5/8"||18 7/32"||14 1/4"||4 3/8"|
|J||40 5/8"||20 1/8"||16"||4 7/8"|
|Grand J||41 1/2"||21"||17"||4 7/8"|
Martin 12-String Acoustic Guitar Dimensions
|Guitar Type/Model||Total Length||Body Length||Body Width||Body Depth|
|D||40 1/2"||20"||15 5/8"||4 7/8"|
|J||41 7/8"||20 1/8"||16"||4 7/8"|
|Grand J||42 5/8"||21"||17"||4 7/8"|
Neither general observations about the tone quality and playability of various shapes and sizes nor tables of precise measurements can tell you which type of steel-string acoustic guitar is right for you. The most important reason to familiarize yourself with the many sizes available is to ensure that the next time you are in the market for a new instrument, you explore all the options. Doing so might well require making trips to three or four different shops, but the extra travel is worth it. Until you have played parlor, auditorium, grand auditorium (concert), dreadnought, and jumbo models, you will never know if you are compromising, when the perfect instrument for your unique playing style was quietly waiting just a few blocks away.