Chord Theory for Guitarists

Learning how to construct chords in jazz, rock, pop, etc… is really not that hard…

Major scales are built with half steps (one fret) and whole steps (two fret) intervals.  A major scale is constructed as such:

1 (W) 2 (W) 3 (h) 4 (W) 5 (W) 6 (W) 7 (h) 8

In C….

C (W) D (W) E (h) F (W) G (W) A (W) B (h) C

Then extensions are the numbers after 8 (which is the same as 1) – 9 (2), 11 (4), 13 (6).  

Here’s everything you need to know about chord symbols.
C5 = 1 5
C = 1 3 5
Cm = 1 b3 5
Sus means suspend the 3rd to the 4th. So 1 4 5.
Sus 2 means 1 2 5.
C7 = 1 3 5 b7
CM7= 1 3 5 7
Cm7 =1 b3 5 b7
CmM7 = 1 b3 5 7
+ or aug means raise the 5 to #5.
Cdim means 1 b3 b5.
Cdim7 means 1 b3 b5 bb7
C half-dim7 is the same as Cm7b5. 1 b3 b5 b7.
C6 = 1 3 5 6
Cm6 = 1 b3 5 6
Cadd 9 means literally add the 9 (2) to the triad – 1 3 5 9 (2)

Upper extensions (9, 11, 13) imply that all the lower extensions are in the chord (13 chord has 1 3 5 b7 9 11 13). M before it means natural 7. Just like the 4 note chords before. Since some of these chords are impossible on the guitar, we end up dropping the less important notes. On a 13 chord, we usually drop the 11 first, then the 5. On an 11 chord, the 9 first, then the 5. On a 9 chord, we can drop the 5. If we’re playing with a bassist, a jazz guitarist will often drop the root – the job of the bass player is to play the root, so it’s taken care of.

Jazz players usually use a #11 in 13 chords (if they include it – rarely in guitar voicings, but piano and orchestrations might). But they rarely call it a C13#11. Strange, but I’ve seen it alot.

If it says b5, #5, b9, #9, #11, b13, then it should be obvious what to do. Rarely have I seen #4, but that would mean the chord has a #4 and a 5 (very dissonant).

There are no b11 or #13, as this would be a M3 or a b7.

aug9 chord would be 1 3 5# b7 9. I’ve seen it before – think dominant chord based on the whole-tone scale.

Jazz musicians often use a triangle for major and a minus for minor. Also a circle for dim, and a circle with a diagonal slash through it for half-dim.

That’s pretty much all there is. It’s amazing how little you need to know to construct billions of different chord voicings.  Feel free to comment with any questions.

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