This was easy enough to do using pencil and paper, although way back in the day they probably didn't even do that, instead relying on a mechanical device called a proportional divider to do the work.Īs mentioned in my book Building the Steel String Acoustic Guitar, the origins of this technique are unknown, but it is likely that builders of early instruments, like lutes with tied on gut frets, observed that the first fret was placed from the nut at approximately the scale length divided by 18 and that the second fret was placed from the second fret at approximately the distance from the bridge to the first fret divided by 18 and that this relationship was the same for all the rest of the frets all the way up the neck. Successively dividing the scale length minus the distance from the nut to the The historical technique for calculating the location for each fret is called the Rule of 18, and it involves Discussions about fret placement accuracy and choosing scale lengths are also included. There are also instructions and calculators for calculating the fret locations of multiscale (so called 'fanned fret') fretboards, for microtonal instruments, and for instruments which feature extended range bass strings.

Of course the info and calculators needed to calculate fret positions for modern instruments, using the 12 th root of 2 are here as well. Information and calculators for the now old-fashioned Rule of 18 are included for those building reproductions of old instruments. Not everyone has an academic interest in how all of this works, so this page includes some easy-to-use calculators that will perform all the calculations for you. There is also information for folks that want to do the calculations to figure out fret positions themselves. For those that are interested, there is a bit of history about the way this has been historically calculated.

This page is all about the calculation of the locations of the frets of a fretted instrument.

Fanned fretboard template