Guitar Frets are laid out to accomplish an equal tempered division of the octave. Each set of twelve frets represents an octave. The twelfth fret divides the scale length exactly into two halves, and the 24th fret position divides one of those halves in half again. The ratio of the spacing of two consecutive frets is formula_1 (twelfth root of two). In practice, luthiers determine fret positions using the constant 17.817—an approximation to 1/(1-1/formula_1). If the nth fret is a distance x from the bridge, then the distance from the (n+1)th fret to the bridge is x-(x/17.817). Frets are available in
Standard tuning and drop down to lower open string notes. This is also more practical for the whole playing range of E–C♯ (on a 21-fret guitar), as it can fit easily into the treble clef when written as E–C♯. Transposing by an octave may be explicitly indicated by a suboctave clef, where a treble clef has an '8' placed below it, or a normal treble clef may be used for simplicity. Other plucked string instruments and their respective standard tunings include: Standard tuning In music, standard tuning refers to the typical tuning of a string instrument. This notion is contrary to that