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Fret Calculator

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Enter your instrument's scale length to find the exact distance from the nut to every fret.

Fret Calculator

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Distance is measured from the nut (fret 0) to the centerline of each fret.

The formula

Distance from nut to fret N = Scale length - (Scale length / 2^(N/12))
Example

A 25.5" scale (standard Fender): fret 12 = 25.5 - (25.5 / 2^1) = 12.75" from the nut - exactly half the scale length, as expected for the octave fret.

Step-by-step guide

  1. Enter your instrument's scale length (the distance from the nut to the bridge saddle).
  2. Read the distance to every fret, up to fret 24.

Why frets get closer together as you go up the neck

Each fret shortens the vibrating string length by a fixed ratio - specifically the twelfth root of two - rather than a fixed distance. This ratio is what makes each fret raise the pitch by exactly one semitone, matching the mathematically even spacing of the 12-tone chromatic scale. Because it's a constant ratio applied repeatedly (not a constant distance), the physical gaps between frets shrink steadily as you move toward the bridge, even though the pitch change between any two adjacent frets is always the same one semitone.

Common mistakes

Using the old "Rule of 18" approximation instead of the exact twelfth-root-of-two formula - the Rule of 18 is a historical shortcut that drifts noticeably out of tune toward the higher frets on a real instrument.
Measuring scale length incorrectly - it should be measured from the nut to the center of the 12th fret, then doubled, not measured all the way to the bridge saddle on instruments with compensated saddles.

Frequently asked questions

What scale length do most electric guitars use?

25.5 inches is the standard Fender scale length, while Gibson-style guitars commonly use 24.75 inches - shorter scales generally feel a bit easier to bend strings on, while longer scales tend to feel tighter and more defined.

Does this work for building a fret board from scratch?

Yes - luthiers use exactly this formula (sometimes called a "fret scale rule") to mark accurate fret positions when building or refretting an instrument.

Why is fret 12 exactly half the scale length?

Fret 12 represents exactly one octave higher than the open string, and halving a vibrating string's length is precisely what raises its pitch by one octave in music theory and physics.

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