F♯ / G♭

F♯ / G♭ is pitch class 6 — the tritone from C, six semitones, the exact midpoint of the octave in equal temperament. F♯ rises from F; G♭ falls from G. Same sounding class, two spellings.

It divides the twelve-step cycle in half: six steps up from C meet six steps down from the octave C. That symmetry is acoustic structure, not a verdict about the note.

In major-triad grammar this class is the root of F♯ major (F♯–A♯–C♯), the major third of D major (D–F♯–A), and the perfect fifth of B major (B–D♯–F♯). Alone it stays a pitch class. A vessel offering opens only for a recognized major triad.

Also known as F sharp · F♯ · G flat · G♭ · Gb · F#