How to Build a Measure on a Fretboard

Different fretboard scale lengths will yield different fret distance measurements.

To understand how to build a measure on a fretboard, you first have to understand that string length affects pitch in a progressive, rather than equidistant, way. This means that the shorter a string becomes, its pitch increases at a disproportionally higher rate. This is why the spacing between frets near the nut of the guitar is wider than the spacing closer to the bridge of the guitar. Fortunately, the rule of 18 is a mathematical equation that allows us to calculate fret position using equal temperament, wherein we divide the fretboard scale length, minus the offset of the previous fret, by 17.817.

Things You'll Need

• Calculator (optional)
• Blank fretboard
• Pencil
• Digital Tape Measure
• Spreadsheet

Instructions

Doing the Math

1. Measure your fretboard scale length. Most guitar fretboards come in common scale lengths. For this example, we’ll use the fretboard scale length of a Fender Stratocaster, which is 25.5 inches.

2. Divide 25.5 by 17.817 to find the distance from the front of the nut to the first fret. In this case, the distance is 1.431 inches.

3. Measure 1.431 inches from the nut and make a mark to show fret placement.

4. Subtract the distance from the nut to the first fret from the original scale length to determine the scale length you will be working with to calculate the distance from the first fret to the second fret. In this case, the new scale length is calculated by subtracting 1.431 from 25.5 to get 24.069.

5. Divide your new scale length by 17.817 to find the distance from the first fret to the second fret. In our example, we will divide 24.069 by 17.817 to get 1.351.

6. Measure 1.351 inches from the first fret and make another mark on the fretboard to show fret placement of the second fret.

7. Repeat the process of subtracting the progressively shorter scale lengths from the original scale length and dividing by 17.817 to calculate and mark the position of all your frets.

Using a Spreadsheet to Build Fret Measures

1. Open your preferred spreadsheet program and enter the fretboard scale length in cell B1 of your spreadsheet.

2. Type this formula into cell B3 to calculate the distance from the nut to the first fret.: “=(B$1-B2)/17.817+B2.”

3. Highlight the cell, which, staying with our example of the scale length being 25.5 inches, shows 1.431, and click on the lower right corner. Drag the formula down the column to get successive fret measurements from the nut. Remember, the numbers will get larger because they are indicating the distance from the nut to each successive fret, not the distance from fret to fret.

4. Type the fret number in column A, starting with fret number one in cell A3. This matches to the fret in column A to the distance from the nut in Column B.

5. Measure and mark the fret distances on your fretboard.

References

• Build Your Guitar: Calculating Fret Distance
• Luitioa Mottla: Calculating Fret Positions
• Fender: American Standard Stratocaster Specs