The root left to the bass player. Frees a finger for a tension.
Bbm9 is Bb, Db, F, Ab and C — Bbm7 with the ninth stacked above it.
It sounds warm, and considerably richer than an m7. The standard voicing for a ii chord once the plain one has been played enough.
Pre-dominant or minor tonic — an m7’s job with more colour.

| Bb | Db | F | Ab | C |
|---|---|---|---|---|
| 1 | ♭3 | 5 | ♭7 | 9 |
Also written Bbmin9, Bb-9 or Bb minor 9. The same chord either way; which spelling you meet depends on who wrote the chart.
Leave the root to the bass player. In a band nobody misses it, and the ear supplies it from the guide tones anyway.
The finger it frees goes to a tension, which is why these sound richer than the shape they came from rather than thinner.
Bbm9 has 14 of them, on the middle four strings, the top four strings and strings 5-3-2-1, from open position up to the 13th — every inversion the chord has: Db in the bass, F in the bass, Ab in the bass and C in the bass. The one to learn first is the C shape at the nut, which is the easiest grip here.
5 of them sit on the middle four strings, so you can run the inversions up one set without changing strings — which is the whole reason to learn them as a family rather than as separate grips.
Five notes and four fingers, so something has to go. Keep Db and Ab (they fix the quality) and C (what the symbol is about). Let F and Bb go, in that order — a perfect fifth says nothing the root has not, and in a band the bass has the root.
Play Bbm9 as a shell — root, third and seventh — and the spare string takes the 11 (Eb) or the 13 (G).
All 7 common shapes as fret numbers, lowest string first. Hover or tap one to see it drawn.
How you get to it. The turn that lands on Bbm9 is Cm7♭5 to F7♭9: the ii and the V of Bb minor, which is where a minor tonic is usually arrived at rather than simply begun on.
In which keys. Every note of Bbm9 belongs to C# major (the vi, the submediant), F minor (the iv, the subdominant), Ab major (the ii, the supertonic) and Bb minor (the i, the tonic).
Every note of Bbm9 is in Bb dorian and Bb natural minor.
Change one note of Bbm9 and you have Bbm69 (the flat seventh becomes the sixth), Bbm7 (drop the ninth), Bbm11 (add the eleventh), BbmMaj9 (the flat seventh becomes the major seventh), Bbmadd9 (drop the flat seventh) or Bb9 (the minor third becomes the major third).
Bbm9 is a minor chord — root, minor third, fifth. Minor chords on every root.
The common shapes and the derived voicings come from different places, and both are explained in how this site is built.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.