The notes of B♭ augmented
B♭ augmented has three notes, B♭, D and F♯: D is a major 3rd above B♭ and F♯ is an augmented 5th above B♭. That gives the formula 1 3 ♯5, two major thirds stacked: a root, a major third and an augmented fifth (8 half steps). In keys written with sharps the same keys are called A♯ augmented: A♯, C𝄪 and E𝄪, a spelling with double sharps or flats that you’ll rarely meet.
How it sounds and where it’s used
An augmented chord sounds dreamy and unresolved, as if a question has been asked. It is a major chord with its fifth raised a half step, and it’s often used as a passing chord, the raised fifth climbing on to the next chord’s note (I, I+, then IV or vi).
- It is B♭ major with the fifth raised a half step: F becomes F♯.
- Its notes are a major third apart all the way round, so D augmented and G♭ augmented use the same three keys: there are only four different-sounding augmented chords.
Fingering
The thumb and little finger take the outer notes. Where two notes are a fourth apart rather than a third, the finger in between is skipped, which is why the inversions change the middle finger. In root position and 2nd inversion the right thumb lands on a black key: move the whole hand a little further in towards the fallboard, so the fingers on white keys stay on them.
| Position | Notes | Right hand | Left hand |
|---|---|---|---|
| Root position | B♭ D F♯ | 1-3-5 | 5-3-1 |
| 1st inversion | D F♯ B♭ | 1-2-5 | 5-3-1 |
| 2nd inversion | F♯ B♭ D | 1-3-5 | 5-2-1 |
Fingers count from the thumb (1) to the little finger (5). Shown low to high, so the left hand starts with 5.
Inversions
The same three notes can be stacked with any of them lowest. 1st inversion puts the third at the bottom: D, F♯ and B♭, written B♭aug/D. 2nd inversion puts the fifth at the bottom: F♯, B♭ and D, written B♭aug/F♯. Whatever is on top, the chord is still B♭ augmented: the lowest note only changes its colour. Pianists choose the position that is nearest to the chord before, so the hand moves by a step instead of jumping.
Keys with B♭ augmented
No major key has an augmented chord. It comes from the harmonic minor, where the raised 7th makes the third chord augmented:
- III+ in G minor (harmonic minor)
A key marked harmonic minor uses the raised 7th of that minor scale, as minor-key music does for its V and vii° chords.
Finding it fast
Count half steps from B♭: 4 and then 4 again (D 4 half steps above B♭ and F♯ 4 half steps above D). Or play the major chord and move the top note up one key. In root position its keys are black, white, black. No other chord of its kind has this shape on the keys, which makes it easy to recognise.
To read it on the page as quickly, practise the shapes with the chord reading quiz, and see how the notes are counted in intervals.