B♭ Dominant 7th Chord (Bb7, A#7) on Piano
The Bb7 chord (Bb dominant 7th) is built from 4 notes: Bb – D – F – Ab. It is also written as A#7.
Play these notes on a MIDI keyboard, your computer keyboard, or the on-screen keys and ChordKeys will name the chord back to you.
Notes and intervals
| Note | Degree | Interval from Bb | Semitones |
|---|---|---|---|
| Bb | 1 | root | 0 |
| D | 3 | major 3rd | 4 |
| F | 5 | perfect 5th | 7 |
| Ab | b7 | minor 7th | 10 |
Inversions
Rearranging which note sits at the bottom gives you 4 playable voicings of the same chord. Inversions let you move between chords with less hand movement.
| Voicing | Notes | Bass note |
|---|---|---|
| Root position | Bb – D – F – Ab | Bb in the bass |
| 1st inversion | D – F – Ab – Bb | D in the bass |
| 2nd inversion | F – Ab – Bb – D | F in the bass |
| 3rd inversion | Ab – Bb – D – F | Ab in the bass |
How the dominant 7th chord is built
Every dominant 7th chord uses the same interval formula: 1 (0 semitones), 3 (4 semitones), 5 (7 semitones), b7 (10 semitones). Starting on Bb and applying that formula produces Bb, D, F, Ab. Learn the formula once and you can build a dominant 7th chord on any of the twelve roots.
Keys that contain Bb7
Every note of Bb7 belongs to these keys, so it will sit naturally in a progression written in any of them.
Other chords on Bb
Dominant 7th chords on other roots
Frequently asked questions
What notes are in a Bb7 chord?
A Bb7 chord contains the notes Bb, D, F, Ab. Those are the 1, 3, 5, b7 degrees measured from the root note Bb.
How do you play Bb7 on piano?
Place your thumb on Bb, then add D and F and Ab above it. With a right hand in root position the common fingering is 1–2–3–5.
Is Bb7 the same as A#7?
Yes. Bb7 and A#7 are enharmonic equivalents — they sound identical and use the same piano keys. Which spelling you use depends on the key you are playing in.