Twelve-Bar Blues

20th Century popular music such as boogie-woogie, rock-n-roll, rhythm and blues are based on the twelve-bar blues. Twelve-bar blues are built on chord 1, chord 4 and chord 5 of the major scale. The chords can be written in roman numerals (I), (IV) and (V). In C major the chords will be chord (I) CEG, chord (IV) FAC and chord (V) GBD. It is straight forward to work out. C major chord (I) is C, then miss a note, then E, then miss a note, then G. Chord (IV) starts with the 4th note of the scale which is F, then follow the same pattern, miss a note, then A, miss a note, then C. Chord (V) starts on the 5th note of the scale which is G, miss a note, then B, miss a note, then D. Below are two examples of chords in C major, GBD (V) and FAC (IV):


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Below are chords (I), (IV) and (V) in different major scales:

C major : (I) CEG, (IV) FAC, (V) GBD
D major : (I) DF#A, (IV) GBD, (V) AC#E
F major : (I) FAC, (IV) BbDF, (V) CEG
G major : (I) GBD, (IV) CEG, (V) DF#A
A major : (I) AC#E, (IV) DF#A, (V) EG#B

The Twelve-Bar Blues

In 4 time | chord (I) | chord (I) | chord (I) | chord (I) | chord (IV) | chord (IV) | chord (I) | chord (I) | chord (V) | chord (IV) | chord (I) | chord (I) ||


Alldis, D. (2000). A classical approach to jazz piano. Milwaukee: Hal Leonard, p.10.


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