F is a musical note, the fourth above C or fifth below C. It is the fourth note and the sixth semitone of the solfège. It is also known as fa in fixed-do solfège.^[1] It has enharmonic equivalents of E♯ (E-sharp)^[2] and G (G-double flat),^[3] amongst others.

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When calculated in equal temperament with a reference of A above middle C as 440 Hz, the frequency of Middle F (F4) is approximately 349.228 Hz.^[4] See pitch (music) for a discussion of historical variations in frequency.

E♯ (German: Eis)^[5] is a common enharmonic equivalent of F, but is not regarded as the same note. E♯ is commonly found before F♯ in the same measure in pieces where F♯ is in the key signature, in order to represent a diatonic, rather than a chromatic semitone; writing an F♮ with a following F♯ is regarded as a chromatic alteration of one scale degree. Though E♯ and F♮ sound the same in any 12-tone temperament, other tunings may define them as distinct pitches.