Root, third and seventh: the guide tones fix the quality, so the fifth is dropped. That is what leaves a string free, so pick a tension to put on top.
Bbmaj9 is Bb, D, F, A and C — Bbmaj7 with the ninth stacked above it.
It sounds a maj7 with more air in it. The ninth argues with nothing here, so it works anywhere a maj7 does.

| Bb | D | F | A | C |
|---|---|---|---|---|
| 1 | 3 | 5 | 7 | 9 |
Tonic — an extended resting chord.
Also written BbM9, BbΔ9, Bbma9 or Bb major 9. The same chord either way; which spelling you meet depends on who wrote the chart.
Root, third and seventh. The third and seventh, the guide tones, are what make the chord major, minor or dominant, so the fifth can go: it says nothing the symbol needs.
Three notes means a spare string, which is the real point. Put a tension on it.
Bbmaj9 has 5 of them, on the middle four strings, the bottom four strings, the top four strings and strings 6-4-3-2, from open position up to the 12th — all in one inversion, so the bass note never moves. The one to learn first is the Bb shape at the nut, which is the easiest grip here.
Start with xx3535 — no barre and low, at the 3rd fret. 1 of the 12 shapes here sits in open position. 7 of the 12 need a barre. Together they cover the neck from the 1st fret to the 14th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| 11021x | open position | F, 2nd inversion | C | barred |
| x33335 | 3rd fret | C, 9th in the bass | A | barred |
| xx3535 | 3rd fret | F, 2nd inversion | A | all fretted |
| 633335 | 3rd fret | Bb, root position | A | barred |
| 657565 | 5th fret | Bb, root position | A | barred |
| 687768 | 6th fret | Bb, root position | C | all fretted |
| xx7768 | 6th fret | A, 3rd inversion | C | all fretted |
| x-x-8-7-10-8 | 7th fret | Bb, root position | C | all fretted |
| 10-8-8-10-10-8 | 8th fret | D, 1st inversion | C | barred |
| x-13-10-10-10-10 | 10th fret | Bb, root position | D | barred |
| x-13-12-14-13-x | 12th fret | Bb, root position | C | all fretted |
| 13-13-12-14-13-x | 12th fret | F, 2nd inversion | C | barred |
The same notes rebuilt from scratch give 13 drop 2, 8 drop 3, 15 rootless and 5 open string voicings, each on its own page.
Tensions. A shell of Bbmaj9, root, third and seventh, leaves a string free, and the tones that belong over it are the #11 (E) and the 13 (G).
How you get to it. The turn that lands on Bbmaj9 is Cm7 to F7 — the ii and the V of Bb — and F7 shares its third and seventh with Cm7, so the hand barely moves between them.
In which keys. Every note of Bbmaj9 belongs to D minor (the ♭VI), F major (the IV, the subdominant), G minor (the ♭III) and Bb major (the I, the tonic).
Every note of Bbmaj9 is in Bb major and Bb lydian.
Change one note of Bbmaj9 and you have Bbmaj7 (drop the ninth), Bbmaj11 (add the fourth), Bbmaj13 (add the sixth), BbmMaj9 (the major third becomes a minor third), Bbadd9 (drop the major seventh) or Bb69 (the major seventh becomes a sixth).
Bbmaj9 is a major chord — root, major third, fifth. Major chords on every root.
On Bbmaj9’s sound and use this page follows Mark Levine, The Jazz Theory Book (Sher Music, 1995). The shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.