Almost every blues you have heard is built on the same twelve bars, and the quickest way to hear them is to count. Four bars on the first chord, two on the second, two back on the first, and then four that turn the form around and hand you back to the top.
In A those chords are A7, D7 and E7. The strip below is one chorus: each box is a bar, and the roman numeral under each chord says which degree of the key it is built on, so the same twelve bars read the same way in any key you move them to.
Twelve bars, in A
The twelve-bar blues in A uses A7 (I7), D7 (IV7) and E7 (V7).
One chorus of the blues. Four bars of A7, two of D7, two of A7, then E7, D7, A7 and E7 to send you round again.
Why all three chords are sevenths
A dominant seventh chord is a major chord with a flat seventh added on top. In most music that flat seventh is restless: it leans on the ear until the music moves somewhere else. A blues does not let it resolve. All three chords are dominant sevenths, so the restlessness never goes away, and that unresolved sound is most of what makes a blues sound like a blues rather than like a folk song in the same key.
A7, wherever your hand is
Strummed from the lowest string to the highest, this grip sounds A, E, G, C♯ and E, which are the degrees 1 5 ♭7 3 5 rather than the 1 3 5 ♭7 of the written chord. The root is the lowest note, so this grip is in root position and sounds the way the written chord suggests. With A in the bass and five strings sounding four notes, the 5 appears more than once.
Strummed from the lowest string to the highest, this grip sounds C♯, E, A, C♯ and G, which are the degrees 3 5 1 3 ♭7 rather than the 1 3 5 ♭7 of the written chord. The lowest note is the 3 rather than the root, so this grip is in first inversion, written A7/C♯. It has the same notes as the root-position grip, but with C♯ in the bass it sounds different. With C♯ in the bass and five strings sounding four notes, the 3 appears more than once.
Strummed from the lowest string to the highest, this grip sounds E, A, E, G, C♯ and E, which are the degrees 5 1 5 ♭7 3 5 rather than the 1 3 5 ♭7 of the written chord. The lowest note is the 5 rather than the root, so this grip is in second inversion, written A7/E. It has the same notes as the root-position grip, but with E in the bass it sounds different. With E in the bass and six strings sounding four notes, the 5 appears more than once.
Strummed from the lowest string to the highest, this grip sounds G, A, E, G, C♯ and E, which are the degrees ♭7 1 5 ♭7 3 5 rather than the 1 3 5 ♭7 of the written chord. The lowest note is the ♭7 rather than the root, so this grip is in third inversion, written A7/G. It has the same notes as the root-position grip, but with G in the bass it sounds different. With G in the bass and six strings sounding four notes, the 5 and ♭7 appear more than once.
Four shapes for A7 on guitar: A7, A7/C♯, A7/E and A7/G.
Every shape here is the same four notes, arranged differently. Play any of them over the first four bars and the chord is stated.
The notes you will play over it
One scale carries you through all twelve bars: the minor pentatonic, five notes that avoid the semitone clashes a full seven-note scale would put under your fingers. In A that is A, C, D, E and G, and at the fifth fret it sits under one hand without moving.
A minor pentatonic, at the fifth fret
Box 1 covers frets 5–8 and holds twelve notes.
This position covers frets 5 to 8, and every note of A Minor Pentatonic lies under one hand there. Five positions like it cover the whole neck, and this is the first of them.
Two of those five notes sound different depending on which chord is underneath them, and the course comes back to them once the form is familiar. For now, hear the form: put the band on, play the scale over the twelve bars, and let your ear follow the chords as they change beneath it.
The twelve bars, with a band
Band · twelve-bar blues in A · shuffle · 84 beats a minute
A band plays the twelve-bar blues in A, shuffled, at 84 beats a minute: A7, A7, A7, A7, D7, D7, A7, A7, E7, D7, A7, E7.
Drums, bass and the shuffle riff, round the twelve-bar blues in A. The bass walks each chord from its root: 1, 3, 5, 6, ♭7, and back down.
This lesson was drafted with the help of AI, so it may contain a mistake. Its diagrams are drawn by Everyfret’s own software. How Everyfret is made