C♯ Half-Whole Diminished at a glance
The half-whole diminished is the standard scale over a dominant 7♭9 chord in jazz. Its symmetry means a phrase transposed by minor third still fits the chord, perfect for fast harmonic motion. Built on the root C♯, the scale takes on the specific colour and pitch range of that key - making it especially useful in genres and registers where C♯ is a comfortable tonal centre.
| Notes | C♯ D E E♯ F𝄪 G♯ A♯ B |
|---|---|
| Formula | 1P · 2m · 3m · 3M · 4A · 5P · 6M · 7m |
| Step pattern | H W H W H W H W |
C♯ Half-Whole Diminished on the piano
Improvisation drone · C♯
Loop the root note as a pad to practice improvising over this scale.
On the piano C♯ Half-Whole Diminished uses three black keys (C♯, G♯ and A♯) and five white. E♯ and F𝄪 are the white keys you'd normally call F and G.
C♯ · D · E · E♯ · F𝄪 · G♯ · A♯ · B
Try C♯ Half-Whole Diminished on the virtual piano
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C♯ Half-Whole Diminished on the guitar
C♯ Half-Whole Diminished - fr 0–12
C♯ Half-Whole Diminished on the staff
Notes of the C♯ Half-Whole Diminished scale
| Degree | Note | Interval | Semitones | Hear |
|---|---|---|---|---|
| 1 | C♯ | unison1P | 0 | |
| 2 | D | minor 2nd2m | 1 | |
| 3 | E | minor 3rd3m | 3 | |
| 4 | E♯ | major 3rd3M | 4 | |
| 5 | F𝄪 | augmented 4th4A | 6 | |
| 6 | G♯ | perfect 5th5P | 7 | |
| 7 | A♯ | major 6th6M | 9 | |
| 8 | B | minor 7th7m | 10 |
What makes C♯ Half-Whole Diminished different
The half-whole diminished scale has eight notes that alternate a half step and a whole step, so its pattern repeats every minor third. That symmetry means there are only three different ones: the scale on C has the same notes as those on E♭, G♭ and A. It holds the 1, 3, 5 and ♭7 of a dominant chord plus the ♭9, ♯9 and ♯11. Its natural fifth and natural 13th are what separate it from the Altered scale over the same chord.
How to use the C♯ Half-Whole Diminished scale
Because C♯ Half-Whole Diminished has fewer or more than seven notes, it doesn't produce a standard set of seven diatonic triads. Instead, build chords by stacking thirds within the scale or use it as a melodic colour over chords drawn from a related diatonic key.
The half-whole diminished is the standard scale over a dominant 7♭9 chord in jazz. Its symmetry means a phrase transposed by minor third still fits the chord, perfect for fast harmonic motion.
Practice tips
Practise the scale starting from each chord tone of the underlying dominant 7♭9 (1, ♭3, ♭5, ♭♭7) — they're all four equivalent because of the symmetry, and that insight is what makes diminished playing fast and fluid.
Formula & step pattern
The C♯ Half-Whole Diminished scale follows an eight-note symmetric scale alternating half-step then whole-step (1, ♭2, ♭3, 3, ♯4, 5, 6, ♭7). Step pattern: H - W - H - W - H - W - H - W. Intervals from the root: 1P · 2m · 3m · 3M · 4A · 5P · 6M · 7m. Memorising the formula lets you transpose the scale to any other root note quickly.
Where you will hear C♯ Half-Whole Diminished
Start with the music described above: listen for C♯ Half-Whole Diminished in it and transcribe a few short phrases by ear. It's the quickest way to learn how the scale sounds.
Questions people ask
What notes are in the C♯ Half-Whole Diminished scale?
The C♯ Half-Whole Diminished scale contains C♯, D, E, E♯, F𝄪, G♯, A♯ and B.
What is the formula for the C♯ Half-Whole Diminished scale?
C♯ Half-Whole Diminished follows an eight-note symmetric scale alternating half-step then whole-step (1, ♭2, ♭3, 3, ♯4, 5, 6, ♭7).
Is C♯ Half-Whole Diminished a major or minor scale?
C♯ Half-Whole Diminished is a half-whole diminished scale. Octatonic scale alternating half then whole steps — symmetric, dissonant, the standard choice over a dominant 7♭9 chord in jazz.
What chords belong to the C♯ Half-Whole Diminished scale?
C♯ Half-Whole Diminished doesn't produce a standard seven-chord diatonic set. Use chords from a related diatonic scale instead.
Which genres use C♯ Half-Whole Diminished?
The half-whole diminished is the standard scale over a dominant 7♭9 chord in jazz. Its symmetry means a phrase transposed by minor third still fits the chord, perfect for fast harmonic motion.
How do you play the C♯ Half-Whole Diminished scale on the piano?
On the piano C♯ Half-Whole Diminished uses three black keys (C♯, G♯ and A♯) and five white. E♯ and F𝄪 are the white keys you'd normally call F and G.
How do I practise the C♯ Half-Whole Diminished scale?
Practise the scale starting from each chord tone of the underlying dominant 7♭9 (1, ♭3, ♭5, ♭♭7) — they're all four equivalent because of the symmetry, and that insight is what makes diminished playing fast and fluid.