Chord · B Dominant 9th
B9 Chord
B9 is B, D#, F#, A and C# — funky, soulful; James Brown territory.
B9 on every instrument
The same 5 notes, 4 sets of hands. Open a diagram for alternate shapes, audio and the mistakes to avoid.
What B9 is made of
B9 (B ninth) is built from the notes B, D#, F#, A, C#, with the interval pattern 1, 3, 5, b7, 9.
Stack 1, 3, 5, b7 and 9 on a root of B and you get B, D#, F#, A and C#. That interval recipe is what makes the chord a ninth chord — move the same shape to another root and the character travels with it, which is why C9 sounds like a transposed B9.
Dominant 9th: Funky, soulful; James Brown territory.
Spelling: the notes above are written the way a score would write them, not simplified to the nearest piano key. That is why this chord is spelled with D♯ rather than its enharmonic equivalent.
Keys that contain B9
All 5 notes sit inside the scale of 2 keys. The roman numeral marks the degree the chord is rooted on.
Major keys
Minor keys
Other chords on B
Same root, different colour.
The same ninth shape, moved
The identical interval recipe, built on other roots.
Questions people ask about B9
- What notes are in the B9 chord?
- B9 is made of B, D#, F#, A and C# — the 1, 3, 5, b7 and 9 degrees of a ninth chord built on B.
- What keys use the B9 chord?
- Every note of B9 belongs to 2 keys: E Major (V), C# Minor (VII). The roman numeral is the scale degree the chord is rooted on.
- How do you play B9 on guitar and piano?
- This page shows B9 on guitar, piano, ukulele and mandolin — 8 voicings in total. Each diagram links to the full instrument page with alternate shapes, audio and common mistakes.
Learn the theory behind it
Why B9 behaves the way it does — the guides that explain the chord instead of just spelling it.