The 12 bar Blues is a pattern of chords which repeats every 12 bars. It is the most common progression in Blues music, and is also used extensively in Jazz. Most 12 Bar Blues tunes are based on a tonality (key type) based on dominant 7th chords. In many Blues songs, all the chords are dominant 7ths. In its basic form, the chords used in a Blues are those built on degrees 1, 4 and 5 of the major scale. So in the key of C, these chords would be C7, F7 and G7, as shown below.
Using Roman numerals these chords become:
Listen to the CD to hear a typical 12 bar Blues. The progression is shown in the key of C with accompanying Roman numerals.The symbol C. which appears above some of the bars is a bar repeat sign, indicating that this bar is identical to the previous one. The last two bars of the progression form a turnaround - a type of ending which leads to the next verse. Turnarounds will be dealt with in a later lesson.