B♭aug chord
B♭ augmented. The augmented triad: a major third and an augmented fifth above the root. Its notes are equally spaced, so it is symmetrical and has no home.
Click a note to hear it
- Notes
- B♭ D F♯
- Formula
- 1 3 ♯5
- Intervals
- P1 M3 A5
- Also written
- B♭+
Notes in B♭aug
B♭aug is spelled B♭ D F♯: three notes stacked from the root B♭.
| Note | Interval above B♭ | Role | Formula |
|---|---|---|---|
| P1 | root | 1 | |
| M3 | third | 3 | |
| A5 | fifth | ♯5 |
Inversions
Putting a different chord tone in the bass gives each inversion. The chord is the same; the bass note changes how it sounds and what it can lead to.
| Position | Notes, low to high | Symbol | Hear it |
|---|---|---|---|
| Root position | B♭ D F♯ | B♭aug | |
| First inversion | D F♯ B♭ | B♭aug/D | |
| Second inversion | F♯ B♭ D | B♭aug/F♯ |
On the piano
The root position voicing, with every chord tone lit in its own colour. Click a key to hear it.
On the guitar
B♭aug in standard tuning. The barre shapes below slide anywhere on the neck, so the same fingers give you every root. Strings run from the lowest (left) to the highest (right); X means do not play that string.
E-shape barre at fret 6
A-shape barre at fret 1
What it sounds like
An augmented triad stacks two major thirds, four semitones each, so its fifth is an augmented fifth, eight semitones above the root. The two intervals are identical, so the chord divides the octave into three equal parts. Each of its three notes can serve as the bass while the chord keeps the same pitches. That symmetry removes any sense of a home note, so the chord sounds open, ambiguous and unresolved. It floats rather than pulls, and listeners often cannot tell its root without a bass note.
How it is used
Augmented triads are rare as diatonic chords. In harmonic minor the third degree is augmented, written III+, so in A minor it is C, E, G♯. In jazz the augmented triad is heard over a dominant, since C7♯5 contains the triad C, E, G♯. Classical composers used it as a passing or colouring sonority. Its raised fifth often moves by a semitone back to the perfect fifth or up to the sixth, and the chord has no fixed resolution.
How it is built
The augmented triad is a root with a major third and an augmented fifth, 0, 4 and 8 semitones above the root. Common symbols are Caug, C+, C♯5 and C(♯5). The fifth, G♯, is the same pitch as A♭, so the chord can be spelled C, E, A♭, though writers rarely do. Only four different augmented triads exist, and each one has three names. The inversions are E+ and G♯+, which contain the same notes as C+.
Which keys contain B♭aug
B♭aug is not built from any one major or minor key’s own notes. It appears through borrowing, alteration or chromatic voice leading, which is part of why it sounds coloured.
Scales that fit B♭aug
Scales that contain every note of the chord, so they can be played over it:
Other B♭ chords
- B♭
- B♭m
- B♭dim
- B♭sus2
- B♭sus4
- B♭5
- B♭6
- B♭m6
- B♭7
- B♭maj7
- B♭m7
- B♭m7♭5
- B♭dim7
- B♭m(maj7)
- B♭7♯5
- B♭7sus4
- B♭add9
- B♭9
- B♭maj9
- B♭m9
- B♭7♭9
- B♭7♯9
- B♭13
How to practise it
Play C, E and G♯ in the right hand, then E, G♯ and C, then G♯, C and E, and hear that the three shapes are one sound. Next play C7♯5 with C, E, G♯ and B♭, and then C7 by lowering the G♯ to G. The one-semitone change removes the augmented sound and turns the chord back into a plain dominant.
Further reading
- Triads and Inversions: Root Position, Sixth, Six-FourHarmony · 6 min
- Chord Symbols Explained: Major, Minor, Seventh and Slash ChordsHarmony · 8 min
Questions
What notes are in a B♭aug chord?
B♭aug contains B♭, D, F♯. That is the root, third, fifth of the chord.
How do you spell B♭ augmented?
Stack the intervals P1, M3, A5 above B♭: B♭, D, F♯.
What other symbols mean B♭aug?
Lead sheets also write it B♭+. They are the same chord.
What is the difference between Caug and C+?
Caug and C+ are two symbols for the same chord: C, E and G♯. The plus sign is common in jazz and pop charts, while aug appears often in textbooks. Neither symbol changes the notes, so a player reads both as the same augmented triad.
Why does an augmented chord sound unresolved?
All of its intervals are major thirds, so no note is clearly a root and the three notes divide the octave evenly. The ear has no strong sense of gravity toward one pitch. Until a bass note or a following chord gives the chord a home, it sounds open, ambiguous and floating.
Where does an augmented triad appear in minor keys?
In harmonic minor, the chord on the third degree is augmented, written III+. The raised seventh of harmonic minor, G♯, becomes the augmented fifth of the chord. In A minor, III+ is C, E and G♯. Composers use it as a colouring chord that sits on the third degree.