The C7#5 piano chord is a 7th sharp 5th chord with the notes C, E, G#, A#. On piano it is played from the keys C, E, G#, A#, root position first, then in inversions. Whether you are learning it for the first time or checking a voicing, this page has the notes, the piano fingerings, the inversions and alternatives, and the progressions it appears in.
What notes are in the C7#5 chord?
The C7#5 chord is a 7th sharp 5th chord, and its notes are fixed: C, E, G#, A#. Every voicing on every instrument uses these same notes, in some order and in some octave — change one of them and you are playing a different chord. The table below lists each note with its interval from the root C, so you can see the structure of C7#5 at a glance. On the piano, C7#5 is the keys C, E, G#, A#, and the inversions above move the same notes around.
| Note | Interval |
|---|---|
| C | Root |
| E | 3 |
| G# | #5 |
| A# | b7 |
The root is C, the note the chord is named after and the note your ear hears as home. Above it, the intervals in C7#5 are 3, #5, b7. Those intervals are the fingerprint of the 7th sharp 5th quality — any chord with the same interval pattern, on any root, is the same kind of chord. On the piano, the notes appear in the order the fingering dictates, but the set of notes never changes.
C7#5 sounds restless and altered, the sound of a V chord with an extra push toward the tonic. That character comes straight from the intervals above, not from the instrument: the same notes on piano, guitar or ukulele carry the same colour, even though the voicing changes. On the piano, play the keys C, E, G#, A# slowly and listen for each note of C7#5 in turn.
Comparing C7#5 with its closest relatives helps to fix it in your ear. In short, 7#5 against dominant 7th: C7#5 raises the 5th to G# where the plain dominant 7th keeps the perfect 5th G. The raised 5th adds lift and tension at the same time. Practise the two chords back to back and listen to the one note that changes — that single note is the difference between the two chords. On the piano, the root-position keys C, E, G#, A# show C7#5 most clearly.
How to play C7#5 on piano
On the piano, C7#5 is played from the keys C, E, G#, A#. In root position the lowest note is C, the root, with the other notes stacked above it in the order C, E, G#, A#. Play it with the right hand first, then with the left hand an octave lower, so both hands know the shape of C7#5 before you try it in a progression.
First inversion of C7#5 puts E in the bass, with the notes in the order E, G#, A#, C. The chord is still C7#5 — the notes have not changed, only their order — but the bass note changes how it connects to the chord before and after it. Use this inversion when the bass line wants to step to E rather than jump to C, and practise moving from root position to this inversion without lifting your hand off the keys more than you must.
Second inversion of C7#5 puts G# in the bass, with the notes in the order G#, A#, C, E. The chord is still C7#5 — the notes have not changed, only their order — but the bass note changes how it connects to the chord before and after it. Use this inversion when the bass line wants to step to G# rather than jump to C, and practise moving from root position to this inversion without lifting your hand off the keys more than you must.
Third inversion of C7#5 puts A# in the bass, with the notes in the order A#, C, E, G#. The chord is still C7#5 — the notes have not changed, only their order — but the bass note changes how it connects to the chord before and after it. Use this inversion when the bass line wants to step to A# rather than jump to C, and practise moving from root position to this inversion without lifting your hand off the keys more than you must.
For fingering, a good starting point for C7#5 in root position in the right hand is thumb on C, then one finger per note in order, with the little finger on the top note A#. For the left hand, mirror it: little finger on the low C and thumb on the top note. When a note is a black key — G#, A# — let your longer fingers take it, since they reach the black keys more easily. Practise C7#5 in root position and first inversion, hands separately, then together, at a slow tempo, and use the Piano Chord Finder to check the voicing on the keyboard.
Common mistakes
These are the mistakes that most often make C7#5 sound wrong on the piano, and each one has a concrete fix. Work through them one at a time rather than trying to fix everything at once.
Voicing it too low. G# low down can sound muddy. Keep the sharpened 5th in a higher octave than the root. On the piano, the root-position keys C, E, G#, A# show C7#5 most clearly.
Playing every inversion with the same hand shape. Each inversion of C7#5 needs its own hand shape, because the notes sit under different fingers. If you force the root-position fingering onto an inversion, the hand cramps and notes get missed. Learn the fingering for each inversion of C7#5 separately, hands apart, before you join them. On the piano, play the keys C, E, G#, A# slowly and listen for each note of C7#5 in turn.
Playing a perfect 5th. If the 5th is G the chord is a plain dominant 7th. The sharpened 5th G# is the note that makes it altered. On the piano, the root-position keys C, E, G#, A# show C7#5 most clearly.
Confusing it with the augmented triad. The augmented triad has no 7th. C7#5 adds the flattened 7th A# to the augmented triad — that 7th is essential. On the piano, play the keys C, E, G#, A# slowly and listen for each note of C7#5 in turn.
Where C7#5 is used
C7#5 is not a diatonic triad in any major or minor key, because it is an extended or altered chord, but its base triad belongs to the key of C major, the key of F major, the key of G major. an altered dominant in jazz, where the sharpened 5th adds tension before a resolution. As a dominant-type chord it also points toward F major, the key a perfect fourth above C, which is the tonic it most often resolves to. That is where C7#5 does its work: not as a home chord, but as a chord that creates movement and then resolves. On the piano, the root-position keys C, E, G#, A# show C7#5 most clearly.
Because C7#5 is an extended or altered chord, it appears in progressions as a colour or a dominant rather than as a diatonic staple. Try it in place of the plain C triad in a progression you already know, and listen to how the extra notes change the feel — that substitution is the usual way extended chords enter real music. The Chord Progression Builder lets you try C7#5 in a progression in any key and hear how it connects to the chords around it. On the piano, C7#5 is the keys C, E, G#, A#, and the inversions above move the same notes around.
The same chord on other instruments is covered in C7#5 on guitar, C7#5 on ukulele, C7#5 on bass, and the scales that fit over it are the C major scale and the C minor pentatonic scale. Learning C7#5 on the piano and then checking it on another instrument is one of the best ways to fix the notes — C, E, G#, A# — in your memory, because the notes stay the same while everything else changes.
Practising C7#5
A short worked example makes C7#5 concrete. Play the four-chord progression F – C – Dm – A# in F major, the key C7#5 most often resolves toward: F – C – Dm – A#. Play each chord for one bar at a slow tempo, and listen to how C7#5 sounds in that sequence — whether it feels like home, like a lift, or like a chord on its way somewhere else. Then play the same four chords in a different order, starting on C7#5 itself, and notice how its character changes when it opens the progression instead of sitting inside it. On the piano, C7#5 is the keys C, E, G#, A#, and the inversions above move the same notes around.
For a second exercise, play C7#5 and then the chord a fourth above C, back and forth, four times each. That move — a chord and the chord a fourth above it — is the most common resolution in Western music, and it is the move C7#5 is built for when it acts as a dominant. Finish by playing C7#5 on its own, slowly, and naming each note out loud as you play it: C, E, G#, A#. Naming the notes while you play them is what turns a shape into knowledge you can use in any key. Test yourself with the Practice Chord Quiz and keep time with the Metronome as the tempo rises. On the piano, the root-position keys C, E, G#, A# show C7#5 most clearly.
Frequently asked questions
What is the difference between C7#5 and C7?
C7 has the perfect 5th G; C7#5 raises it to G#. C7#5 sounds tenser and more exotic, and it is used as an altered dominant in jazz. On the piano, the keys above put that note under your fingers.
Where is C7#5 used?
C7#5 is an altered V chord in jazz and minor-key progressions, used before a resolution to the tonic. It adds lift and tension to a dominant chord. On the piano, the keys above put that note under your fingers.
How do you play C7#5 on the piano?
In root position, play the keys C, E, G#, A#, with C as the lowest note. That is the basic shape of C7#5 on the piano. The inversions above put a different note in the bass, and the Chord Inverter shows every inversion of C7#5 on the keyboard.
What is the first inversion of C7#5?
The first inversion of C7#5 puts E in the bass, with the notes in the order E, G#, A#, C. The chord is still C7#5 — only the bass note has changed — and it is the inversion to use when the bass line steps to E.
Which fingers do you use for C7#5 on piano?
In the right hand, start with the thumb on C and one finger per note in order, ending with the little finger on A#. In the left hand, mirror it with the little finger on the low C. Longer fingers take the black keys, so check which notes of C7#5 are black keys before you settle on a fingering.