A#7 Chord on Piano
A#7 = A# – D – F – G# (Root, Major 3rd, Perfect 5th, Minor 7th)
Under its everyday name, Bb7, this chord is a genuine workhorse of wind-band and blues repertoire, resolving into E-flat major, one of the most common keys concert bands ever play. Spelled on this site as A#, D, F, and G#, it takes the one-black-key A# major triad and adds a second raised note, G#, as the flattened seventh — two black keys and two white ones, evenly split. As a dominant seventh, it's formally the V7 of D#, resolving with equal conviction to either D# major or D# minor.
The hand alternates terrain here rather than settling into one type of key — thumb on black A#, middle finger and ring finger on white D and F, pinky reaching back to black G#. That tension comes from the tritone between D and G#, the chord's third and flattened seventh, the same interval that drives every dominant seventh toward resolution. Because E-flat major turns up constantly in concert band writing, the flat-spelled twin of this chord, Bb7, becomes a workhorse dominant for wind ensembles, doing precisely the same harmonic job that A#7 performs under its sharp-spelled identity. Blues pianists in flat keys also reach for this exact shape, since Bb blues progressions are nearly as common in horn-driven jazz repertoire as the more familiar C or F blues forms.
Voicings
Root Position
1st Inversion
How to Practice It
Build the shape from the A# major triad, reaching the pinky up to the black key G# while the middle finger and ring finger hold their white-key positions on D and F. Because the notes split evenly between black and white, this chord is genuinely useful for practicing the terrain-shifting hand movement that real four-note jazz and band voicings demand, rather than the more uniform reach of an all-black or all-white shape. Alternate your resolutions, too — into D# minor one day, D# major the next — so neither destination starts to feel like the automatic default.
Common Progressions
- A#7 – D#m (V7 – i in D# minor), a strong minor-key resolution
- A#7 – D# (V7 – I in D# major), the identical shape resolving to the brighter tonic instead
- D#m – A#7 – D#m (i – V7 – i), A#7 working as a turnaround inside D# minor
- Gm – A#7 – D#m (a minor-key approach into A#7's dominant function)
- Cm – A#7 – D# (a chromatic approach resolving strongly onto D# major)
FAQ
- Why is this chord almost always called Bb7 instead of A#7?
- Bb7 resolves into E-flat major, one of the most common keys in concert band and blues repertoire, so the flat spelling is far more practical to read even though the physical shape is identical to A#7.
- Does A#7 resolve only to major, or minor too?
- Both — as a dominant seventh, it pulls with equal force toward D# major or D# minor, since either tonic shares the identical dominant chord.
- How are the black and white keys distributed in A#7?
- Evenly split down the middle: the root and seventh, A# and G#, are raised keys, while the third and fifth, D and F, sit flat.
- Is this chord common in horn-driven blues repertoire?
- Yes, under its flat-spelled identity as Bb7 — Bb blues progressions are nearly as common in jazz and horn-driven repertoire as the more familiar C or F blues forms.
- How many raised keys sit inside this shape overall?
- Two — the root A# and the added seventh G#, leaving the third and fifth (D and F) as landmarks on the white-key surface.
- Why does this particular tritone feel unstable to the ear?
- D and G# sit exactly six semitones apart, splitting the octave precisely in half — that symmetry is what makes a tritone sound suspended and unresolved rather than settled in either direction.
- Is this chord's spelling ever seen directly in beginner method books?
- Rarely — most students meet it far more often as Bb7, since flat notation is the practical standard for wind-band and blues repertoire built around E-flat major.
- Is this shape harder to reach than F7 or C7?
- About the same overall difficulty, though the mixed black-and-white geography here asks the hand to alternate terrain rather than lean mostly toward one key color the way F7 and C7 do.
- Does this chord's flat-spelled twin appear in beginner jazz method books?
- Yes — as Bb7, it's a common early dominant seventh introduced once a student starts working through flat-key blues and jazz standards.
A#7 on other instruments: A#7 on Guitar, A#7 on Ukulele. Related: how chords are built, chord finder.