Fret Distance Calculator

In equal temperament, each step increases frequency by a constant ratio: r = 2^(1/N), where N is the divisions per octave.

The vibrating string length must shrink by the inverse ratio. For fret n: L_n = L · 2^(-n/N). The distance from the nut to fret n becomes: d_n = L - L_n = L · (1 - 2^(-n/N)).

This calculator optionally adds a compensation value to L to model a slightly longer effective scale.

1. Enter the instrument scale length and select the input unit.
2. Pick an output unit for the generated fret table.
3. Set divisions per octave (12 for standard equal temperament).
4. Choose how many frets you want to generate.
5. Optionally add compensation and open string frequency.
6. Press Calculate to view results above the form.
7. Use Download CSV or Download PDF to export.

1. Equal Temperament as a Ratio System

Modern fretted instruments commonly use equal temperament, where one octave doubles frequency. If an octave is split into N equal steps, each step multiplies frequency by 2^(1/N). This calculator uses that ratio to convert musical steps into precise geometric positions along a string.

2. Why the Distances Shrink Toward the Bridge

Frequency is inversely related to vibrating length for a fixed string and tension. As frets rise in pitch, the needed vibrating length decreases exponentially. That is why the first fret spacing is relatively large, while upper frets are tightly clustered.

3. Typical Scale Length Data

Common scale lengths include 650 mm for classical-style instruments, around 648 mm for many steel‑string designs, and 25.5 in (647.7 mm) for many electric models. Shorter scales increase fret spacing slightly and reduce string tension for the same pitch, which can change feel and intonation behavior.

4. Interpreting Key Reference Frets

The 12th fret is an important checkpoint: it should sit at half the effective scale length because it represents one octave. For example, a 650 mm effective scale places the 12th fret near 325 mm from the nut. Use this to sanity‑check measurements on templates and printed layouts.

5. Compensation and Real‑World Setup

Real instruments often require a slightly longer effective scale at the saddle because pressing a string increases tension. Typical compensation values can range from about 1 mm to 3 mm, depending on string gauge, action height, and playing style. This calculator lets you model that shift so the entire fret table aligns with your setup target.

6. Microtonal and Non‑Standard Divisions

While N=12 is standard, builders also use 19, 24, or other divisions for microtonal designs. Increasing N reduces the pitch step size and creates more frets per octave. The same physics applies, but careful tooling and labeling become more critical as spacing tightens.

7. Using the Output Table for Fabrication

The table provides distance from the nut, spacing from the previous fret, and the remaining vibrating length. For workshop use, many builders mark from the nut because it minimizes cumulative error. If you must step‑mark sequentially, use the “distance from previous” column and re‑verify at the 12th fret.

8. Accuracy, Rounding, and Tolerance

Small rounding choices can matter when spacing becomes tight above the 15th fret. Use higher precision when exporting or printing, then maintain consistent measurement technique. A practical tolerance band of ±0.1 mm is common for many builds, but your tooling determines achievable accuracy.

1) What does “divisions per octave” mean?

It is the number of equal pitch steps that make up one octave. For most instruments it is 12, meaning each fret raises pitch by the constant ratio 2^(1/12).

2) Why is the 12th fret close to half the scale?

The 12th fret represents one octave above the open string. An octave doubles frequency, so the vibrating length must be halved, placing the fret at about 50% of the effective scale.

3) How does compensation affect fret placement?

Compensation slightly increases the effective scale length to account for tension rise when fretting. It shifts all fret distances by a small amount while keeping the equal‑ratio spacing pattern.

4) Can I use this for bass, ukulele, or other strings?

Yes. Enter the correct scale length, choose the number of frets, and keep N=12 for standard tuning. The same length‑ratio physics applies to any fretted string instrument.

5) What if I want microtonal frets?

Set divisions per octave to 19, 24, or your preferred value. The calculator will generate positions using the same exponential rule, producing more frets per octave and smaller spacing.

6) Which column should I use for marking the fretboard?

Marking distance from the nut is usually safest because it avoids accumulating small errors. The “distance from previous” column is helpful for cross‑checking or sequential marking when needed.

7) Why do upper frets feel crowded?

Each higher pitch requires a fixed ratio decrease in vibrating length. Because ratios compound, the absolute distance between adjacent frets shrinks rapidly as you move toward the bridge.