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
Eight-string guitar Eight-string guitar An eight-string guitar is a guitar with two more strings than the usual six, or one more than the Russian guitar's seven. Eight-string guitars are less common than six and seven-string guitars, but they are used by a few classical, jazz, and metal guitarists. The eight-string guitar allows a wider range, or non-standard tunings (such as major-thirds tuning), or both. Various non-standard guitars were made in the 19th century, including eight-string guitars played by Italians Giulio Regondi and Luigi Legnani. In the 1940s, American lap steel guitars generally standardized with eight strings. Tuning was usually based on either