Extended Chords and Jazz Harmony: 9ths, 11ths, and 13ths

Once you are comfortable with seventh chords, the next frontier is extended chords — 9ths, 11ths, and 13ths. These are the sounds that define jazz, neo-soul, R&B, gospel, and lo-fi hip hop. They add richness, complexity, and emotional depth that simple triads and seventh chords cannot achieve on their own.

This guide explains how extended chords are built, the most common types, and how musicians actually voice and use them in practice.

How Extended Chords Are Built

Extended chords follow the same principle as seventh chords: keep stacking thirds. A triad has three notes (root, 3rd, 5th). A seventh chord adds another third to reach the 7th. Extended chords continue that chain:

• 9th chord = 7th chord + one more third (reaching the 9th)
• 11th chord = 9th chord + one more third (reaching the 11th)
• 13th chord = 11th chord + one more third (reaching the 13th)

A full 13th chord theoretically contains seven different notes — every note of the scale: root, 3rd, 5th, 7th, 9th, 11th, and 13th. After the 13th, the next third would bring you back to the root (two octaves up), so 13th chords are as far as tertian harmony extends.

Important: The 9th is the same pitch class as the 2nd, the 11th is the same as the 4th, and the 13th is the same as the 6th — they are just named as extensions because they sit above the 7th in the chord stack.

Ninth Chords

Ninth chords are the most common extended chords and appear across nearly every genre. Here are the main types:

Dominant 9th (9)

Formula: 1 – 3 – 5 – ♭7 – 9

Example — C9: C – E – G – B♭ – D

The dominant 9th adds a natural 9th to a dominant seventh chord. It sounds funky, bright, and energetic. This is the quintessential chord of funk and soul — think of every classic James Brown or Stevie Wonder groove.

Major 9th (maj9)

Formula: 1 – 3 – 5 – 7 – 9

Example — Cmaj9: C – E – G – B – D

The major 9th is lush, warm, and sophisticated. It takes the dreamy quality of a maj7 chord and adds even more openness. Neo-soul artists like Erykah Badu and D’Angelo use maj9 chords constantly.

Minor 9th (m9)

Formula: 1 – ♭3 – 5 – ♭7 – 9

Example — Cm9: C – E♭ – G – B♭ – D

The minor 9th is smooth and mellow, adding a gentle brightness to the minor seventh sound. It is a favourite in jazz ballads, lo-fi beats, and R&B slow jams. The natural 9th over a minor chord gives it a Dorian flavour.

Other Ninth Chord Variations

• Dominant 7♯9 (the “Hendrix chord”): 1 – 3 – 5 – ♭7 – ♯9. The clash between the major 3rd and the ♯9 (enharmonically a minor 3rd an octave up) creates a gritty, aggressive sound. Jimi Hendrix made this chord famous in “Purple Haze.”
• Dominant 7♭9: 1 – 3 – 5 – ♭7 – ♭9. A darker, more tense dominant chord common in minor key jazz progressions.

Eleventh Chords

Eleventh chords add another layer of harmonic complexity. However, they come with an important caveat about avoid notes.

Dominant 11th (11)

Formula: 1 – 3 – 5 – ♭7 – 9 – 11

Example — C11: C – E – G – B♭ – D – F

In theory, a dominant 11th contains both the major 3rd (E) and the natural 11th (F). These two notes are only a half step apart, creating a harsh, muddy clash. In practice, musicians almost always omit the 3rd when voicing a dominant 11th chord, which is why these often sound similar to suspended chords.

Minor 11th (m11)

Formula: 1 – ♭3 – 5 – ♭7 – 9 – 11

Example — Cm11: C – E♭ – G – B♭ – D – F

Minor 11th chords do not have the same avoid-note problem because the minor 3rd (E♭) and the 11th (F) are a whole step apart. This makes m11 chords smooth and usable as-is. They are common in modal jazz, neo-soul vamps, and ambient music.

The ♯11 Solution

To avoid the 3rd/11th clash in major and dominant contexts, jazz musicians often raise the 11th by a half step:

• Dominant 7♯11: 1 – 3 – 5 – ♭7 – ♯11 (often includes the 9th too)
• Major 7♯11 (Lydian chord): 1 – 3 – 5 – 7 – ♯11

The ♯11 sits a tritone above the root, creating a bright, Lydian-flavoured sound that avoids clashing with the major 3rd. This is one of the most distinctive and beloved sounds in jazz harmony.

Thirteenth Chords

Thirteenth chords represent the fullest expression of tertian harmony. They use virtually every note of the scale.

Dominant 13th (13)

Formula: 1 – 3 – 5 – ♭7 – 9 – (11) – 13

Example — C13: C – E – G – B♭ – D – (F) – A

The dominant 13th has a warm, sophisticated, and slightly bluesy quality. The 13th (which is the same note as the 6th) adds sweetness on top of the dominant seventh tension. In practice, the 11th is usually omitted to avoid the clash with the 3rd.

Minor 13th (m13)

Formula: 1 – ♭3 – 5 – ♭7 – 9 – 11 – 13

Example — Cm13: C – E♭ – G – B♭ – D – F – A

Minor 13th chords are rich and complex. The natural 13th over a minor chord gives it a distinctly Dorian colour. These chords appear in sophisticated soul, gospel, and jazz arrangements.

Major 13th (maj13)

Formula: 1 – 3 – 5 – 7 – 9 – (♯11) – 13

Example — Cmaj13: C – E – G – B – D – (F♯) – A

The major 13th is the ultimate “pretty” chord — open, lush, and full of colour. It often includes a ♯11 to maintain the Lydian brightness and avoid the natural 11th clash.

Practical Voicings: You Do Not Play All the Notes

Here is the crucial reality of extended chords: no one plays all seven notes at once. Pianists and guitarists select the most important tones and omit the rest. The general guidelines are:

1. Always keep the 3rd and 7th — these define the chord quality
2. Always include the extension that names the chord (the 9th, 11th, or 13th)
3. Often omit the 5th — it adds little to the chord’s character
4. Often omit the root — especially in a band context where the bass player covers it
5. Omit the 11th in dominant and major chords to avoid the avoid-note clash

A practical Cmaj9 voicing on piano might be just four notes: E – B – D – G (the 3rd, 7th, 9th, and 5th). The bass player handles the C. This kind of sparse, spread voicing is what gives jazz piano its characteristic open sound.

For guitar, extended chords often use only four or five strings, dropping the root and fifth and focusing on the guide tones (3rd and 7th) plus the extension.

An Interactive Chord Finder can help you discover which notes are essential and which are optional, letting you build practical voicings note by note.

Tensions and Avoid Notes

In jazz theory, extensions are often called tensions — notes that add colour and interest to a chord. But not all tensions work equally well in every context:

• Available tensions blend smoothly with the underlying chord
• Avoid notes create a half-step clash with a chord tone, muddying the harmony

The classic avoid note is the natural 11th over a major or dominant chord (clashing with the 3rd). In minor chords, the ♭13 can also be problematic, clashing with the 5th and pushing the chord toward a different quality.

Understanding which tensions are available on each chord type is a core skill in jazz arranging and improvisation.

Common Usage Across Genres

Jazz: Extended chords are the standard vocabulary. A jazz ii-V-I in C major might be voiced as Dm9 – G13 – Cmaj9 rather than simple triads.

Neo-soul and R&B: Artists like D’Angelo, Erykah Badu, and Anderson .Paak build entire grooves around maj9, m11, and 13th chords. The lush harmonic palette is a defining feature of the genre.

Gospel: Gospel pianists are masters of extended voicings, using 9ths, 11ths, and 13ths with chromatic passing chords to create rich, moving harmonic textures.

Lo-fi and chill music: The warm, slightly dissonant quality of maj7 and m9 chords (often with detuned or tape-saturated processing) defines the lo-fi aesthetic.

Getting Started with Extended Chords

Begin with ninth chords — they are the most accessible. Take chord progressions you already know and upgrade each seventh chord to its ninth chord equivalent. A ii-V-I becomes Dm9 – G9 – Cmaj9. Listen to how the added 9ths open up the sound.

Then experiment with 11ths and 13ths, paying attention to avoid notes and practical voicings. Use the Interactive Chord Finder to visualise these chords and hear which notes contribute the most to each chord’s character.

Extended chords are not just for jazz musicians. Once you hear them, you will recognise them everywhere — and you will have a powerful new toolkit for creating harmony that moves and inspires.