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Compound Radius Calculator

Joel Bennett

Fret Distance Calculator

Scale Length =
  • From Fret :
  • Nut
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  • From Nut :
  • Nut
    0
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Compound Radius Calculator

E to E @ Nut =
E to E @ 12th =
Nut Radius =
Radius Point =

Radius Point Result =

Instructions:

The formulas for this calculator are from Stewart MacDonald.

*This calculator is meant for Imperial measurements (Inches).

*You must perform the fret distance calculation using your scale length before using the compound radius calulator, as it relies on the results of the former.

*All input values must be in decimal form – rounding to 3 decimal places is more than enough for accuracy.

The “E to E” values are measurements of distance between the high E string and low E string at the specified points (at the nut and the 12th fret, specifically).

The “Radius Point” value is the distance from the nut to the point where you would like to know the radius.

This application could also be called “The Perfect Fretboard Building Tool” – or something like that. It incorporates the Fret Distance Calculator because the formulas used to calculate a compound radius rely on measurements given from the specified scale (particularly, the distance from the nut to the 12th fret).

So once you’ve done both calculations, you’ll be looking at everything you need to build a PERFECT fretboard (except the wood, of course).

If the instructions are unclear, I’ll try to simplify. You need to know five numbers to do this:

  1. Your desired scale length.
  2. The desired radius at the nut.
  3. The exact distance between the high E string and the low E string at the nut.
  4. The exact distance between the high E string and the low E string at the 12th fret.
  5. The distance from the nut to the point at which you’d like to know the radius (fret distances from the nut will already be provided on the left side).

Enter the scale length in the fret distance calculator and press the button there FIRST. Only then can the compound calculator give you the correct results based on the rest of your measurements.

The “Radius Point” measurement can be adjusted beyond the fretboard to account for extra length that a compound radius router/sander jig might add. For anything behind the nut, you can place a negative number as the radius point.

Don’t forget to include the extra little length of the fretboard past the last fret in your calculations!

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