Fret Position Placement Calculation Action String Height

Determining the correct fret position on a guitar string involves calculating the placement based on the string height and action. This guide explains the formula, provides a calculator, and offers practical advice for musicians.

Introduction

When setting up a guitar, one of the critical steps is determining the correct fret position. The fret position affects the playability and sound of the instrument. The calculation involves the string height and the action (the distance from the fretboard to the string at the nut).

Understanding how to calculate fret positions helps luthiers and musicians ensure consistent intonation and playability across all strings and frets.

Formula

The standard formula for calculating fret position is based on the scale length of the guitar and the fret number. However, when considering string height and action, we use the following approach:

Fret Position (mm) = (Scale Length × (2^(Fret Number/12) - 1)) - (String Height - Action)

Where:

Scale Length - The distance from the nut to the bridge (typically 25.5 inches or 647.7 mm for a standard guitar)
Fret Number - The fret position you want to calculate (0 for the nut, 1 for the first fret, etc.)
String Height - The height of the string at the desired fret position
Action - The distance from the fretboard to the string at the nut

Note: This formula assumes a standard 12-fret-per-octave guitar. For non-standard tunings or instruments, adjustments may be needed.

How to Use the Calculator

Use the calculator in the sidebar to determine the fret position based on your string height and action. Enter the required values and click "Calculate" to get the result.

The calculator will display the fret position in millimeters and provide a visual representation of the calculation.

Example Calculation

Let's calculate the fret position for the 5th fret on a standard guitar with the following parameters:

Scale Length: 647.7 mm
Fret Number: 5
String Height: 2.5 mm
Action: 1.5 mm

Using the formula:

Fret Position = (647.7 × (2^(5/12) - 1)) - (2.5 - 1.5)

Fret Position ≈ (647.7 × 0.2973) - 1.0

Fret Position ≈ 193.2 - 1.0 ≈ 192.2 mm

The calculator will confirm this result and show it in the result panel.

FAQ

What is the difference between action and string height?

Action refers to the distance from the fretboard to the string at the nut, while string height is the vertical position of the string at a specific fret. Both are important for proper guitar setup.

How does the scale length affect fret position?

The scale length determines the overall length of the string between the nut and bridge. A longer scale length results in longer fret positions.

Can this calculator be used for other instruments besides guitars?

Yes, the same principles apply to other stringed instruments like bass guitars, ukuleles, and mandolins, as long as you adjust the scale length accordingly.