Chord · Bb Major 7♯5
B♭maj7♯5 Chord
B♭maj7♯5 is Bb, D, F# and A — lydian augmented sound; modern jazz.
B♭maj7♯5 on every instrument
The same 4 notes, 2 sets of hands. Open a diagram for alternate shapes, audio and the mistakes to avoid.
What B♭maj7♯5 is made of
Bb Major 7♯5 (Bb major 7♯5) is built from the notes Bb, D, F#, A, with the interval pattern 1, 3, #5, 7. A common major 7♯5 chord across many styles.
Stack 1, 3, #5 and 7 on a root of B♭ and you get Bb, D, F# and A. That interval recipe is what makes the chord a major seventh sharp five chord — move the same shape to another root and the character travels with it, which is why Cmaj7♯5 sounds like a transposed B♭maj7♯5.
Major 7♯5: Lydian augmented sound; modern jazz.
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 B♭ rather than its enharmonic equivalent.
Keys that contain B♭maj7♯5
No major or natural-minor key contains all 4 of these notes — this one gets borrowed.
Chords like this one sit outside the diatonic set — they arrive as secondary dominants, borrowed chords or passing harmony. Browse every key to see which progressions pull it in.
Other chords on B♭
Same root, different colour.
The same major seventh sharp five shape, moved
The identical interval recipe, built on other roots.
Questions people ask about Bbmaj7#5
- What notes are in the Bbmaj7#5 chord?
- Bbmaj7#5 is made of Bb, D, F# and A — the 1, 3, #5 and 7 degrees of a major seventh sharp five chord built on Bb.
- What keys use the Bbmaj7#5 chord?
- No major or natural-minor key contains all 4 notes of Bbmaj7#5. Chords like this arrive as borrowed harmony — secondary dominants, harmonic-minor colour, or chromatic passing chords — rather than as one of a key's native chords.
- How do you play Bbmaj7#5 on guitar and piano?
- This page shows Bbmaj7#5 on guitar and piano — 4 voicings in total. Each diagram links to the full instrument page with alternate shapes, audio and common mistakes.
- Is Bbmaj7#5 the same as A#maj7#5?
- Yes. Bbmaj7#5 and A#maj7#5 are enharmonic — identical pitches written two different ways. Which spelling you use depends on the key you are in; Bbmaj7#5 is the spelling this site treats as canonical.
Learn the theory behind it
Why B♭maj7♯5 behaves the way it does — the guides that explain the chord instead of just spelling it.