What is the standard 12-bar blues harmonic progression?

• A. I-I-I-I IV-IV-I-I V-IV-I-I
• B. I-IV-V-I IV I I I
• C. I-V-vi-IV I-V
• D. I-vi-ii-V I-IV-I I

Answer: (A)

The essential idea is the 12-bar blues form, a 12-measure cycle built around the I, IV, and V chords. The standard pattern keeps the I chord for most of the piece, uses the IV for a couple of measures to create contrast, then returns to I, followed by a quick turn to the V before resolving back to I. Specifically, four measures on I, two on IV, two on I, one on V, one on IV, and two on I is the classic setup. This exact sequence gives the familiar blues feel and a clear turnaround to bring the harmony back to the tonic. The progressing that matches this pattern is the one that represents the traditional 12-bar blues form. The other sequences either place the IV and V in different spots or introduce chords (or progressions) that belong to other styles, so they don’t fit the standard 12-bar blues structure.