Scale cardinality classifies scales by how many distinct pitches they contain before repeating at the octave. Each cardinality produces a distinct sonic character and serves different musical purposes, from the simple five-note pentatonic to the complete twelve-note chromatic.
The octave note is not counted in cardinality. A seven-note scale has seven distinct pitches within the octave, with the eighth note being the octave repetition.
Pentatonic scales contain 5 notes per octave with no half steps between adjacent notes, creating inherently consonant relationships. These scales consist of whole-tone steps and minor thirds. Every transposition shares five notes with neighboring scale patterns on the circle of fifths.
Common variants include major pentatonic (bright, accessible sound), minor pentatonic (blues and rock backbone), and regional scales like Egyptian and Hirajoshi with distinctive cultural flavors.
Six-note scales contain 6 notes per octave, offering more melodic variety than pentatonic without the full complexity of seven-note systems. The blues scale adds the characteristic "blue note" (flatted fifth) to minor pentatonic. The whole tone scale, built entirely of whole steps, is symmetrical and divides the octave into six equal parts, creating tonally ambiguous, suspended quality favored by impressionist composers.
Seven-note scales contain 7 notes per octave and form the foundation of Western classical music, jazz, and popular music. The half-step relationships create leading tones that enable complex harmonic progressions. Each scale degree can support a distinct chord, forming the basis for tonal harmony.
Major scale provides bright, stable harmony while natural minor offers a melancholic counterpart. Harmonic minor features a raised seventh degree for dramatic tension and Middle Eastern flavor. Church modes (Dorian, Phrygian, Lydian, Mixolydian, Locrian) each offer distinct emotional colors from the same note collection. Major and minor scales account for the vast majority of classical, pop, rock, and country compositions.
Eight-note scales contain 8 notes per octave and are characterized by symmetrical construction. Diminished scales alternate whole and half steps in repeating patterns that repeat every three semitones (minor third), dividing the octave into equal parts. The whole-half pattern works over diminished chords, while half-whole works over dominant seventh chords. Bebop major and bebop dominant scales add a chromatic passing tone to major or minor scales to help land chord tones on downbeats. The symmetry creates harmonic ambiguity valued in modern classical composition and essential for advanced jazz improvisation.
The chromatic scale contains 12 notes—every pitch in the Western system arranged in half steps. It is tonally neutral, containing all possible tonal centers simultaneously and establishing no particular key or harmonic center. Unlike other scales that select a subset of pitches, the chromatic scale includes every available pitch with no gaps.
Used as a practice tool for technical development that builds finger control and familiarity with the instrument, for chromatic passing tones that connect melody notes, and in serialist and atonal composition where composers use the complete chromatic collection as source material. Not used as a melodic or harmonic foundation like other scales, but for embellishment and sophisticated movement across all musical styles.