Extended & Altered Chords
Keep stacking 3rds past the 7th and you reach the extensions — the 9th, 11th and 13th — the colours of jazz, soul, funk and film. Bend those tensions a semitone and you get alterations (♭9, ♯9, ♯11, ♭13): the spice that makes a dominant chord pull hard toward home.
The Core Idea: keep stacking 3rds
A triad is R–3–5. Add another 3rd for the 7th, and again for the 9th, 11th and 13th. Past the octave the degrees get new names: the 2nd becomes the 9th, the 4th the 11th, the 6th the 13th. Once you pass the 13th you've used all seven notes — there's nowhere higher to go.
In practice you rarely play all seven notes — guitarists drop the 5th (and often the root, letting the bass cover it) to free fingers for the tensions that actually define the sound.
Root note — hear every chord in this key
Extensions — added colour
Diatonic tensions stacked on top. They enrich a chord without demanding resolution.
Major 9th
Cmaj9Lush and open — a major 7th with the 9th on top. Think warm jazz and neo-soul.
Dominant 9th
C9The classic funk/blues dominant. The 9th brightens the pull of a plain 7th.
Minor 9th
Cm9Smooth and sophisticated — the go-to lush minor for soul and jazz.
Minor 11th
Cm11Dreamy and suspended — the 11th sits happily over a minor chord (no clash with the ♭3).
Dominant 13th
C13The full dominant sound — the 5th is usually dropped so the 13th can sing. Big-band V chord.
Six-nine
C6/9A stable, resolved alternative to maj7 — a tonic chord with colour but no leading-tone tension.
Alterations — tension & pull
Chromatically raised or lowered tensions, almost always on a dominant (V) chord, to intensify the pull to the tonic.
Dominant 7♭9
C7♭9Dark, dramatic dominant — the ♭9 adds bite. Ubiquitous resolving to a minor chord.
Dominant 7♯9
C7♯9The "Hendrix chord" — the ♯9 rubs against the major 3rd for a gritty, bluesy edge.
Dominant 9♯11
C9♯11The Lydian-dominant colour — floaty and modern. The ♯11 replaces the perfect 5th.
Dominant 7♭13
C7♭13A tense, "outside" dominant. The ♭13 (=♯5) darkens the resolution — pure altered-scale sound.
Altered Dominant
C7altMaximum tension: every available tension stacked. The V chord that resolves hardest to i.
Half-diminished (m7♭5)
Cm7♭5The ii of a minor key — a minor 7th with a flat 5th. Restless, wants to move to the V.
Reading the colours
Formula Reference
| Chord | Degrees |
|---|---|
| Major 9th maj9 | R 3 5 7 9 |
| Dominant 9th 9 | R 3 5 ♭7 9 |
| Minor 9th m9 | R ♭3 5 ♭7 9 |
| Minor 11th m11 | R ♭3 5 ♭7 9 11 |
| Dominant 13th 13 | R 3 ♭7 9 13 |
| Six-nine 6/9 | R 3 5 6 9 |
| Dominant 7♭9 7♭9 | R 3 5 ♭7 ♭9 |
| Dominant 7♯9 7♯9 | R 3 5 ♭7 ♯9 |
| Dominant 9♯11 9♯11 | R 3 ♭7 9 ♯11 |
| Dominant 7♭13 7♭13 | R 3 ♭7 ♭9 ♭13 |
| Altered Dominant 7alt | R 3 ♭7 ♭9 ♯9 ♭13 |
| Half-diminished (m7♭5) m7♭5 | R ♭3 ♭5 ♭7 |
Play these voicings on the neck
See fingerings for 9th chords in the Chord Visualizer, or learn where altered dominants live in a ii–V–I.