4 Levels of 2 5 1 6 Jazz Guitar Chords

What’s the 2 5 1 6 Progression

The 2–5–1–6 progression (often written ii–V–I–vi) is a very common chord sequence in jazz and many other styles.

It’s built from the degrees of a major scale:

2 (ii) → minor 7 chord

5 (V) → dominant 7 chord

1 (I) → major 7 chord

6 (vi) → minor 7 chord

Example in C Major:

C major scale:
C – D – E – F – G – A – B

The chords become:

Dm7 (ii)

G7 (V)

Cmaj7 (I)

Am7 (vi)

So the progression is:

Dm7 – G7 – Cmaj7 – Am7

This will serve as the basis for the 4 exercises below.

Why It’s Important in Jazz

✔︎ The ii–V–I is the most important progression in jazz.

✔︎ Adding the vi chord creates a smooth cycle and often sets up another ii–V.

✔︎ It appears in countless standards (Autumn Leaves, Rhythm Changes variations, etc.).

✔︎ It’s essential for comping, chord melody, and improvisation.

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Harmonic Tricks Used

Diminished 7 Substitution For Dominant 7 Chord

A diminished 7 substitution for a dominant 7 chord means you can replace a dominant 7 chord with a diminished 7 chord built from its 3rd, 5th, 7th, or ♭9 — because they share almost the same notes.

In the exercises below, G7 is replaced by Bdim built on its third.

Because of the symmetry of the diminished 7 chord you can also play Ddim7, Fdim7 and A♭dim7.

Chord Equivalence (min7 and 6)

A major 6 chord is the same notes as the minor 7 chord built on its 6th degree.

Example pattern:

C6 ↔ Am7

F6 ↔ Dm7

G6 ↔ Em7

Different function, same notes, different tonal center.

Diminished 7 Symmetry

A diminished 7 chord is symmetrical because it is built entirely from minor thirds.

Example:
B°7 = B – D – F – A♭
Each note is 3 semitones apart.

Because of this:

✔︎ Any note in the chord can act as the root

✔︎ There are only 3 unique diminished 7 chords in total

✔︎ Inverting the chord gives the same notes

So:

B°7 = D°7 = F°7 = A♭°7

Same notes, different starting point.

That’s what we mean by symmetry.

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