String Spread at Pickup Projector

What this tool is for

Project measured outer-string spread at a pickup location without assuming a bridge or pickup standard. Pickup fit tools compare user-entered physical measurements. They do not maintain a product catalog, predict tone, or authorize routing, drilling, forced installation, or structural changes.

Use it when you can describe the current state and need a defensible next check. It is not a shortcut around inspection: preserve the starting state, change one variable, and verify the result under the same conditions.

Before you begin

Tune the guitar, identify nut and bridge witness points, measure the outer-string center spread at each endpoint, and measure along the scale direction to the intended pickup center.

Use a stable, tuned instrument unless the page specifically investigates tuning.
Name the physical reference, unit, and test condition beside every important number.
Keep the original measurements so any reversible change can be returned to baseline.

Input guide

Input and display unit: sets the interpretation and display unit; do not mix units elsewhere in the same run.
Scale length: defines speaking length or the geometric reference used by the calculation.
Outer-string spread at nut: supplies a measured geometric quantity whose datum and resolution should be written down.
Outer-string spread at bridge: supplies a measured geometric quantity whose datum and resolution should be written down.
Nut to pickup center: provides a measured or counted input; confirm the allowed range and repeat the reading before relying on it.

Input labels describe evidence, not targets. A placeholder demonstrates format only; it is never a recommendation for a particular guitar.

How the result should be read

Use the projection to compare candidates before ordering, then verify actual string centers over the real opening or installed pickup. A small difference is a measurement question, not a tonal verdict.

Read priorities from top to bottom, but stop as soon as new evidence contradicts an earlier assumption. Save or print the result ticket with the entered conditions so another person can reproduce the decision.

Method and logic

The calculation linearly interpolates outer-string spread between the measured nut and bridge endpoints at the entered fraction of scale length. It makes no assumption about bridge family or pickup standard.

The page keeps calculation and diagnostic claims deliberately bounded. Display rounding improves readability, while the underlying logic uses entered values; descriptive branches report relative tendencies and the evidence needed to confirm them.

Worked example

A 35 mm nut spread and 52 mm bridge spread at the midpoint of a 648 mm scale produce a projected spread of 43.5 mm. The real pickup location must still be measured because alignment can be offset.

The example demonstrates reasoning, not a universal setup specification. Substitute real measurements and repeat the final test before accepting the next action.

Assumptions and limitations

The model assumes straight, centered string paths between endpoints. Multiscale layouts, lateral offsets, compensation, neck taper errors, and nonparallel witness points require direct measurement.

Instrument design, service history, measurement error, and player technique can outweigh a calculator or checklist. Where manufacturer instructions exist for the exact hardware, use those instructions and record the revision consulted.

Safety and stop conditions

Stop for abnormal resistance, cracking, heat, odor, electrical sensation, moving wood or joints, a measurement that cannot be repeated, or any step that would remove material without a confirmed cause. Secure strings and stored mechanical energy before hardware work. Refer structural, fret-cutting, mains-powered, or uncertain repairs to a qualified technician.

Related workflow

Pickup Pole Spacing Matcher — Compare measured string spread with candidate outer-pole spacing and an explicit alignment tolerance.
How to Measure Pickup Fit — Measure the string path, part, cavity, ring, and screw centers.
Pickup Fit Measurement Reference — Keep external size, opening, route, and mounting spans distinct.

Open the related page that answers the next unresolved question; do not run every tool as if every system needs adjustment.