Harmony
12-bar blues
The 12-bar blues is a twelve-bar chord progression built on the I, IV and V chords of a key, usually played as dominant sevenths, such as A7, D7 and E7 in A.
What is the 12-bar blues?
The 12-bar blues is a progression twelve bars long that uses only three chords: the I, IV and V of the key. In A, that means A7, D7 and E7. The form grew out of early 20th-century African American blues and became the backbone of rock and roll, rhythm and blues and a large part of jazz.
All three chords are normally dominant seventh chords: A7 (A C# E G), D7 (D F# A C) and E7 (E G# B D). That flat seventh never quite resolves, which is why the blues sounds gritty even on the home chord.
What are the chords of a 12-bar blues in A?
| Bars | Chords |
|---|---|
| 1 to 4 | A7, A7, A7, A7 |
| 5 to 8 | D7, D7, A7, A7 |
| 9 to 12 | E7, D7, A7, E7 |
Think of it as three four-bar phrases: a statement on the I, an answer on the IV, then the V-IV-I descent that closes the form. Bar 12, the E7, is the turnaround: it pulls you back to bar 1.
A very common variation is the quick change: play D7 in bar 2 (A7, D7, A7, A7) and keep the rest the same. In E the chords are E7, A7 and B7; in G they are G7, C7 and D7. To see the degrees in Roman numerals next to other styles, open the chord progression library.
How do you play a 12-bar blues on guitar?
The classic accompaniment is the two-note shuffle on the low strings. For A7: open A string plus D string 2nd fret (an A5 power chord), then move that finger to the 4th fret (A6). Alternate A5 and A6, two hits per beat.
- A7: open A string + D string, frets 2 and 4
- D7: open D string + G string, frets 2 and 4
- E7: open low E string + A string, frets 2 and 4
Play it with a swing feel (long-short eighth notes) at about 80 BPM, resting the edge of your picking hand lightly on the strings for a tight, muted sound.
Which scale should you use to solo over a blues in A?
The obvious starting point is the A minor pentatonic: A C D E G, in the first box at the 5th fret (low E string, 5th fret = A). Add Eb and you have the blues scale, whose flat fifth works as a passing note.
To sound less like a scale and more like music, aim for chord tones in that same position:
- over A7, C# (the third), G string 6th fret;
- over D7, C (the seventh), G string 5th fret;
- over E7, G# (the third), D string 6th fret.
Sliding from C to C# as the A7 comes back is one of the most recognisable moves in blues guitar.
Key takeaways
- The 12-bar blues uses I, IV and V in three four-bar phrases.
- In A: A7 A7 A7 A7 | D7 D7 A7 A7 | E7 D7 A7 E7.
- The A5-A6 shuffle on the low strings covers the whole form.
- Solo with the minor pentatonic, then target the third of each chord.
Frequently asked questions
Why does the blues use seventh chords on every degree?
In a standard major key, only the V chord is naturally a dominant seventh. The blues puts one on every chord as a stylistic choice: the flat seventh (G over A7, C over D7) comes from the blues scale and the vocal tradition. It is what makes the form recognisable within two bars.
What is the difference between a major and a minor blues?
A minor blues keeps the 12-bar form but makes the I and IV chords minor. In A minor: Am7 Am7 Am7 Am7 | Dm7 Dm7 Am7 Am7 | E7 Dm7 Am7 E7. Many jazz versions play F7 then E7 in bars 9 and 10.
What is the best key for a blues on guitar?
E and A are the most comfortable because the root of the I chord is an open bass string: E7, A7, B7 or A7, D7, E7. Horn players often prefer G, C, F or Bb, which you can cover easily with barred seventh chords or a capo.
Related terms
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