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
Seven-string guitar Seven-string guitar The seven-string guitar adds one additional string to the more common six-string guitar, commonly used to extend the bass range (usually a low B) or also to extend the treble range. The additional string is added in one of two different ways: by increasing the width of the fingerboard such that the additional string may be fretted by the left hand; or, by leaving the fingerboard unchanged and adding a "floating" bass string. In the latter case, the extra bass string lies next to the existing bass strings, but free of the fingerboard in similar fashion as the