In music, an eight-bar blues is a common blueschord progression. Music writers have described it as "the second most common blues form"[1] being "common to folk, rock, and jazz forms of the blues".[2] It is often notated in 4 4 or 12 8 time with eight bars to the verse.
Eight-bar blues progressions have more variations than the more rigidly defined twelve bar format. The move to the IV chord usually happens at bar 3 (as opposed to 5 in twelve bar); however, "the I chord moving to the V chord right away, in the second measure, is a characteristic of the eight-bar blues."[1]
In the following examples each box represents a 'bar' of music (the specific time signature is not relevant). The chord in the box is played for the full bar. If two chords are in the box they are each played for half a bar, etc. The chords are represented as scale degrees in Roman numeral analysis. Roman numerals are used so the musician may understand the progression of the chords regardless of the key it is played in.
Jimmy Rogers' "Walkin' By Myself"[11] (somewhat unorthodox example of the form):
I7
I7
I7
I7
IV7
V7
I7
V7
Howlin Wolf's version of "Sitting on Top of the World" is actually a 9 bar blues that adds an extra "V" chord at the end of the progression. The song uses movement between major and dominant 7th and major and minor fourth:
I
I7
IV
iv
I7
V
I7 IV
I7 V
The first four bar progression used by Wolf is also used in Nina Simone's 1965 version of "Trouble in Mind", but with a more uptempo beat than "Sitting on Top of the World":
I
I7
IV
iv
I VI7
ii V
I IV
I V
The progression may be created by dropping the first four bars from the twelve-bar blues, as in the solo section of Bonnie Raitt's "Love Me Like a Man" and Buddy Guy's "Mary Had a Little Lamb":[13]
IV7
IV7
I7
I7
V7
IV7
I7
V7
There are at least a few very successful songs using somewhat unusual chord progressions as well. For example, the song "Ain't Nobody's Business" as performed by Freddie King at least, uses a I–III–IV–iv progression in each of the first four bars. The same four bar progression is used by the band Radiohead to make up the bulk of the song "Creep".