C Sharp Augmented Chord
The c sharp augmented chord (C♯aug) is C♯, E♯, A. Play those 3 notes together and you have it.
No key contains it; it is the chord a piece passes through on the way to another key.
The keyboards below are live. Press the notes and the page grades what you played, so you can check the shape without guessing, root position first, then both inversions, which is where chord playing stops sounding like exercises and starts sounding like music.
How to play C♯aug on piano
Play the C Sharp Augmented Chord (Root Position)
Tap the highlighted keys — any order.
Right hand: fingers 1, 3 and 5 on C♯, E♯, A, thumb on the C♯.
Left hand: the same notes, fingers 5, 3 and 1, little finger on the C♯.
Press all the notes at once rather than rolling them, and listen for whether they arrive together. A chord that is nearly simultaneous is the single most common thing that makes playing sound robotic, and it is fixable in a week.
Try it on the keyboard above. Any octave counts.
C♯aug, first inversion
Play the C Sharp Augmented Chord (First Inversion)
Tap the highlighted keys — any order.
E♯, A, C♯: C♯aug with the third, E♯, at the bottom. A chord chart writes it C♯aug/E♯. The outside fingers span a augmented 5th, E♯ up to C♯, so the right hand takes it with fingers 1, 2 and 5.
Use it when the chord before or after shares notes with it: the hand moves one or two keys instead of jumping, and the bass line steps rather than leaps. Play C♯aug/E♯ on the keyboard above, then C♯aug in root position, and listen to which way each one leans.
C♯aug, second inversion
Play the C Sharp Augmented Chord (Second Inversion)
Tap the highlighted keys — any order.
A, C♯, E♯: C♯aug with the fifth, A, at the bottom. A chord chart writes it C♯aug/A. The outside fingers span a augmented 5th, A up to E♯, so the right hand takes it with fingers 1, 3 and 5.
Use it when the chord before or after shares notes with it: the hand moves one or two keys instead of jumping, and the bass line steps rather than leaps. Play C♯aug/A on the keyboard above, then C♯aug in root position, and listen to which way each one leans.
How the C♯aug chord is built
Count in semitones from the root, C♯:
| Note | Semitones above the root | Interval |
|---|---|---|
| C♯ | 0 | root |
| E♯ | 4 | major 3rd |
| A | 8 | augmented 5th |
That pattern is the chord. Move the whole shape up two semitones and you have the same chord on a different root, which is why learning one quality well is worth more than memorizing twelve chords separately.
A semitone is the distance to the very next key, whether black or white. Count them on the keyboard above if the numbers do not mean much yet; they will after a few chords.
Where C♯aug turns up
C♯aug belongs to no major or minor key. It is C♯ with the fifth pushed up a semitone to A, and its three notes are each a major third apart, which makes it symmetrical: the same three keys, started on E♯ or on A, are E♯aug and Aaug. Nobody can hear which note is the root, and composers use exactly that to slide from one key to another.
You will meet it where C♯ would be (G Flat Major, D Flat Major, A Flat Major, E Flat Minor), for one beat, on the way to the chord a semitone or a fourth away. Play C♯, then C♯aug, then C♯ again on the keyboard above and hear the fifth strain upward and settle.
Practicing C♯aug
Five minutes, in this order:
- Right hand, root position. C♯, E♯, A, played together, four times.
- Both inversions, in order, going up and then back down. Say which one you are on.
- Left hand alone, the same three steps. It is always the weaker hand and always the one people skip.
- Hands together, left hand playing just the root while the right hand plays the chord.
- Find it in a piece. A chord you have only met in isolation does not stay learned.
Do not chase speed here. A chord you can place accurately without looking is worth more than four you can nearly place quickly.