G♭ (G-flat) or Sol Bémol is the seventh semitone of the solfege.
It lies a diatonic semitone above F and a chromatic semitone below G, thus being enharmonic to F♯ (F-sharp) or Fa Dièse . However, in some temperaments, it is not the same as F♯. G♭ is a major third below B♭, whereas F♯ is a major third above D (a minor third below A).
When calculated in equal temperament with a reference of A above middle C as 440 Hz, the frequency of the G♭ semitone is approximately 369.994 Hz. See pitch (music) for a discussion of historical variations in frequency.