---
title: Blues Harmony
category: Jazz Harmony
slug: blues-harmony
related: [ii-v-i, seventh-chords, tritone-substitution, reharmonization]
url: https://fourthshub.com/docs/blues-harmony
---

# Blues Harmony

The blues is the foundation of American music and one of the most versatile harmonic frameworks in existence. Its 12-bar form has been the basis for countless compositions across jazz, rock, R&B, country, and beyond.

## The Basic 12-Bar Blues

The simplest form uses only three chords, all dominant 7ths:

```
| I7  | I7  | I7  | I7  |
| IV7 | IV7 | I7  | I7  |
| V7  | IV7 | I7  | V7  |
```

In the key of Bb (the most common jazz blues key):

```
| Bb7 | Bb7 | Bb7 | Bb7  |
| Eb7 | Eb7 | Bb7 | Bb7  |
| F7  | Eb7 | Bb7 | F7   |
```

The use of *all* dominant 7th chords (even on I and IV) is unique to blues harmony. In standard functional harmony, only the V chord is dominant.

## Jazz Blues

Jazz musicians enrich the basic form with ii-V motion, chromatic passing chords, and substitutions:

```
| Bb7    | Eb7    | Bb7    | Bdim7  |
| Eb7    | Edim7  | Bb7    | G7     |
| Cm7    | F7     | Bb7 G7 | Cm7 F7 |
```

Key additions: diminished passing chords (Bdim7 connecting Bb7 to Eb7), a ii-V turnaround in the last two bars (Cm7-F7), and a secondary dominant (G7 targeting Cm7).

## Bird Blues (Parker Blues)

Charlie Parker's sophisticated version adds extensive ii-V motion:

```
| Bbmaj7 | Cm7 F7  | Bbmaj7  | Bbm7 Eb7 |
| Abmaj7 | Am7 D7  | Bbmaj7  | G7       |
| Cm7    | F7      | Bbmaj7  | Cm7 F7   |
```

This version treats the melody and harmony almost like a standard, with rapidly changing ii-V motion.

## Minor Blues

The minor blues uses a minor i chord and typically draws from natural minor or Dorian:

```
| Cm7   | Cm7   | Cm7   | Cm7  |
| Fm7   | Fm7   | Cm7   | Cm7  |
| Dm7b5 | G7alt | Cm7   | G7alt|
```

The ii-V in bars 9-10 (Dm7b5-G7alt) comes from harmonic minor and creates a strong resolution to the minor tonic.

## Blues Tonality

Blues exists in a unique harmonic space where major and minor coexist. The "blue notes" (b3, b5, b7 over a major chord) create the characteristic ambiguity. This is why dominant 7th chords work on every degree — the b7 accommodates the blues scale's tensions. Understanding blues harmony is essential regardless of what genre you play.