B♭ Augmented Chord (Bbaug, A#aug) on Piano
The Bbaug chord (Bb augmented) is built from 3 notes: Bb – D – F#. It is also written as A#aug.
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 | augmented 5th | 8 |
Inversions
Rearranging which note sits at the bottom gives you 3 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# | Bb in the bass |
| 1st inversion | D – F# – Bb | D in the bass |
| 2nd inversion | F# – Bb – D | F# in the bass |
How the augmented chord is built
Every augmented chord uses the same interval formula: 1 (0 semitones), 3 (4 semitones), #5 (8 semitones). Starting on Bb and applying that formula produces Bb, D, F#. Learn the formula once and you can build a augmented chord on any of the twelve roots.
Other chords on Bb
Augmented chords on other roots
Frequently asked questions
What notes are in a Bbaug chord?
A Bbaug chord contains the notes Bb, D, F#. Those are the 1, 3, #5 degrees measured from the root note Bb.
How do you play Bbaug on piano?
Place your thumb on Bb, then add D and F# above it. With a right hand in root position the common fingering is 1–3–5.
Is Bbaug the same as A#aug?
Yes. Bbaug and A#aug are enharmonic equivalents — they sound identical and use the same piano keys. Which spelling you use depends on the key you are playing in.