Lesson 26 · All 12 keys

Add9 Chord Trainer

Learn how an add9 chord is built one semitone-count at a time — a major triad plus a 9th on top, with no 7th of any kind in between — then put it to work with three MIDI exercises: playing all 12 add9 chords around the circle of fourths, and 5 jazz plus 5 gospel chord progressions that show off its bright, wide-open, "at rest" color, in every key.

How an add9 chord is built

An add9 chord is a 4-note chord — a major triad with one more note stacked on top. Unlike every 7th chord in Lessons 13-17, that extra note is a 9th, added straight on top of the intact triad, with no 7th at all in between. Every add9 chord — in any of the 12 keys — is built the exact same way, by counting semitones to the right from a root note:

  1. Start on the root — the note that names the chord.
  2. Count 4 semitones to the right to land on the major 3rd.
  3. From there, count 3 more semitones to the right (7 semitones from the root) to land on the perfect 5th.
  4. From there, count 7 more semitones to the right (14 semitones from the root — an octave plus a major 2nd) to land on the 9th.
Example — D add9 (Dadd9): start on D, count 4 semitones right to reach F♯, 3 more to reach A, then 7 more to reach E (an octave and a step above the root). D‑F♯‑A‑E is the Dadd9 chord. The pattern 4, 3, 7 (14 semitones total from root to top) is what makes a chord an "add9 chord" — every one of the 12 add9 chords is this same shape, just moved to start on a different key.
The 9th is the exact same pitch class as the major 2nd degree — just moved up an octave so it rings out above the 3rd and 5th instead of clashing right next to the root. Because there's no 7th at all, an add9 chord never pulls anywhere the way a dominant 7th or major 7th does — it's a bright, wide-open, "at rest" color, which is exactly why jazz, pop, and gospel pianists reach for it as a shimmering substitute for a plain triad. Watch out for two mix-ups: an add9 chord is not a "9th chord" (which stacks a 9th on top of a full dominant or major 7th chord — 7th included), and it's not a sus2 chord (which replaces the 3rd with a 2nd rather than adding a 9th above an intact triad).

Try it: pick a root and build the chord step by step

Step 1 of 4
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Chord toneNoteSemitones from rootMIDI #

All 12 add9 chords at a glance

ChordRoot+4 semitones → 3rd+3 semitones → 5th+7 semitones → 9th

This MIDI exercise plays all 12 add9 chords, one after another, moving around the circle of fourths — each chord's root sits a perfect 4th (5 semitones) above the last one: C → F → B♭ → E♭ → A♭ → D♭ → G♭/F♯ → B → E → A → D → G → back to C. Every chord is played as a full 4-note add9 chord (root, 3rd, 5th, and 9th together).

Chord 1 of 12
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The 12 chords, in circle-of-fourths order

#ChordRoot3rd5th9th

Five jazz chord progressions that put the add9 chord to work — mostly as a bright, open substitute for a plain triad or a 6th chord instead of a 7th chord. Pick a progression and play it in one key or cycle through all 12.

Key of C
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Progression in C

DegreeChordNotes

Five gospel chord progressions built the same way. Pick a progression and play it in one key or cycle through all 12.

Key of C
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Progression in C

DegreeChordNotes