Twelve-bar Blues - Structure

Structure

In the key of C, one basic blues progression, E from above, is as follows (Benward & Saker 2003, 186):

Popular music symbols

C C C C or C7 C7 C7 C7 F F C C or F7 F7 C7 C7 G G C C or G7 G7 C7 C7

Different notations

Chord	Function	Numerical	Roman numeral
Tonic	T	1	I
Subdominant	S	4	IV
Dominant	D	5	V

Chords may be also represented with a few different notation systems. A basic example of the progression would look like this, using T to indicate the tonic, S for the subdominant, and D for the dominant, and representing one chord. In Roman numeral analysis the tonic is called the I, the sub-dominant the IV, and the dominant the V. (These three chords are the basis of thousands more pop songs which thus often have a blues sound even without using the classical 12-bar form.)

Using said notations, the chord progression outlined above can be represented as follows. (Kernfeld 2007)

Functional notation: T T T T S S T T D D T T

Roman-numeral notation: I I I I IV IV I I V V I I

The first line takes four bars, as do the remaining two lines, for a total of twelve bars. However, the vocal or lead phrases, though they often come in threes, do not coincide with the above three lines or sections. This overlap between the grouping of the accompaniment and the vocal is part of what creates interest in the twelve bar blues.