F♯

F♯ (eff-sharp or F-sharp; also known as fa dièse or fi) is the seventh semitone of the solfege.

It lies a chromatic semitone above F and a diatonic semitone below G, thus being enharmonic to Sol Bémol or Gmusic|♭ (G-flat). However, in some temperaments, it is not the same as G-flat. G-flat is a perfect fifth below D-flat, whereas F sharp is a major third above D. Thus Gmusic|flat is slightly lower in pitch.

When calculated in equal temperament with a reference of A above middle C as 440 Hz, the frequency of the Fmusic|♯ semitone is approximately 369.994 Hz. See pitch (music) for a discussion of historical variations in frequency.