ExMI’s Fret-Placement Calculator

Last modified 8-28-2009

Click here to skip the notes and go straight to the calculator


The Experimental Musical Instruments Fret Placement Calculator is made to calculate fret locations for fretted stringed instruments.

Most western instruments are designed to produce the standard western scale known as 12-tone equal temperament. With the ExMI Fret-Placement Calculator you can generate fret locations for this scale, or you may choose any other equal temperament scale (up to 60). At present, the program is not set up to handle just intonations. (Just intonations are problematic for fretted instruments, but not impossible). For fuller background information on equal and just scales and their application to fretted instruments, click here.

Whatever scale you choose, the program calculates locations for frets over three-fourths of your given string length, covering a range of two octaves. That’s probably more than you’ll need. You can use the results for as many frets as the instrument calls for and ignore the rest. Remember that frets spaced closer than about a quarter inch apart will be difficult to finger.

PROCEDURE

In the calculator below, fill in the information as needed, then click “Calculate.”

1) SCALE LENGTH: Indicate the string scale length for the intended instrument. This is the active sounding length for the open string, from bridge to nut.

2) TONES PER OCTAVE: Most users will want to use the standard scale known as 12-tone equal temperament, so they will accept the default value of 12. For those that wish to explore equal temperaments with other numbers of tones per octave, this is the place to indicate the number of tones per octave for the equal temperament scale you want. (For more information on 12-tone and non-12-tone equal temperaments, click here .)

3) STRETCH COMPENSATION: Check this box if you want stretch-compensation to be built into the results. Stretch compensation slightly offsets the fret placements relative to the mathematical ideal to correct for the pitch-sharpening effects of string stretching when the string is pressed down behind the fret. For more information on stretch-compensation and alternative ways of dealing with this question, click here.

4) CALCULATE: Click the “Calculate” button. Your results will appear momentarily.

More information: scale types , stretch compensation

Scale Length
in inches
or centimeters
Tones per Octave
Stretch Compensation

For another fret-spacing calculator on the web (existing in a simple online version and a fuller downloadable version), visit http://www.dougsparling.com/software/.

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