Half-Whole Diminished Scales on Piano

The half-whole diminished scale is the mirror image of the whole-half diminished — an eight-note octatonic scale that alternates half steps and whole steps. It is the dominant diminished scale, used over dominant 7th chords (especially 7♭9, 7♯9, and 13♭9) to add chromatic tension. Like its sibling, only three distinct half-whole collections exist.

Formula: H–W–H–W–H–W–H–W (alternating half and whole steps)

Intervals: P1–m2–A2–M3–A4–P5–M6–m7–P8

Scale degrees: 1–♭2–♯2–3–♯4–5–6–♭7

Sound: Dominant, tense, bebop, chromatic

Also known as: Dominant diminished scale, octatonic scale (H–W rotation)

The dominant vs. diminished distinction: Whole-half goes with diminished 7th chords. Half-whole goes with dominant 7th chords. The easy way to remember: the starting interval determines the chord quality. Half-step first = dominant function (contains a major third and flat seventh). Whole-step first = diminished function (contains a minor third and diminished seventh).