F♯ (musical note)
F♯ (eff-sharp or F-sharp; also known as fa dièse or fi) is the seventh semitone of the solfège.
It lies a chromatic semitone above F and a diatonic semitone below G, thus being enharmonic to Sol Bémol or G♭ (G-flat). However, in some temperaments, it is not the same as G♭. 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 F♯ above middle C (or F♯4) is approximately 369.994 Hz. See pitch (music) for a discussion of historical variations in frequency.
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