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A Guide to Acoustic Guitar Sizes – Part II: Big Guitars

Guitars with lower bout widths of 15 inches or less are in general based on classic designs and designations from Martin. Part II of this guide to acoustic guitar sizes looks at guitars with lower bouts greater than 15 inches wide. Things are not as clear cut here as with smaller guitars. The variety of distinctive shapes is larger than for small guitars and some designations, e.g., dreadnought, cannot be as reliably tied to the lower bout width when you start comparing guitars from different makers.

Dreadnought guitars.

MakeSizeFrets to bodyLower BoutDepthBody LengthScaleNut WidthExampleSize Name
MartinD1215.6254.7520.937525.41.75HD-28VSDreadnought
MartinD1415.6254.8752025.41.6875D-28Dreadnought
Taylor#1014164.6252025.51.6875210 DLXDreadnought
GibsonDove etc (square shoulder dreadnought)1416.25????DoveDreadnought

Dreadnought guitars have a distinctive shape with a wider waist, a deeper body and a lower bout of approximately 16 inches compared to most guitars. But as you can see from the table, the lower bout width varies slightly among the major guitar makes. Dreadnoughts with 12 frets to the body are rare now but the original dreadnought was a 12-fret instrument. A 12-fret dreadnought is going to have sloped shoulders. The shoulders became more squared when the switch was made to 14-frets at the neck joint.

The Gibson Dove is pictured on the right.


Guitars as Big as a Dreadnought but Not Quite a Dreadnought.

MakeSizeFrets to bodyLower BoutDepthBody LengthScaleNut WidthExampleSize Name
Taylor#1414164.6252025.51.6875214ceGrand Auditorium
GibsonAJ1416??25.5? Advanced Jumbo
GibsonJ451416????J45 

Some of these guitars are 14-fret slope shouldered dreadnoughts and some are maybe something else (such as the 214ce from Taylor). They all have a 16 inch lower bout and aren’t the traditional 14-fret dreadnought with squared shoulders on the upper bout.

The Gibson Advanced Jumbo is shown on the left. One of Gibson’s most successful and popular acoustic guitars, the J-45, is shown on the right.


Jumbos or Lower Bouts wider than 16 inches.

MakeSizeFrets to bodyLower BoutDepthBody LengthScaleNut WidthExampleSize Name
Taylor#161416.254.6252025.51.75316Grand Symphony
Taylor#181416.75520.62525.51.75818eGrand Orchestra
GibsonSJ14174.75???SJ-200Super Jumbo

The Gibson Jumbo (J or SJ, 100 or 200) is a big guitar. They are distinctively different fromdreadnoughts because they have a narrower waist. The SJ-200 has a 17 inch lower bout and Gibson likes to let you know it is nicknamed the King of the Flattop guitars. It was the guitar played Elvis.


4 thoughts on “A Guide to Acoustic Guitar Sizes – Part II: Big Guitars”

  1. Not very useful for me as my question right now is about differences between J-45s and Hummingbirds. Lower bout 15″ 31/32, upper bout 11″ 5/16, body length 20″ 1/8, that’s the J-45…What about Hummingbirds

    1. Sorry lower bout would be 11″ 7/16 (not 5/16) as I wrote). Most forums would not have taken my answer without registering, so I was pretty sure my answer wouldn’t be accepted. Then I didn’t pay much attention (this is the Gibson J-45)…

      1. I hope you find the answer you’re looking for, Bernie.fr. My measurement information comes from published specifications, mostly from the manufacturers. I wish they all provided these numbers to their customers. You should also know the exact measurements can change from one model year to the next. If you’ve read my blog you will see I have a preference for smaller guitars. I don’t own any Gibson acoustic guitars right now so can’t take measurements of my own. Good luck.

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