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
Guitar chord chord is lowered by an octave. Drop-two chords are used for sevenths chords besides the major-minor seventh with dominant function, which are discussed in the section on intermediate chords, below. Drop-two chords are used particularly in jazz guitar. Drop-two second-inversions are examples of openly voiced chords, which are typical of standard tuning and other popular guitar-tunings. "Alternatively voiced" seventh chords are commonly played with standard tuning. A list of fret-number configurations for some common chords follows: Already in basic guitar-playing, inversion is important for sevenths chords in standard tuning. It is also important for playing major chords. In standard tuning,