#guitar

Guitar and luthier maths as an API, computed locally and deterministically — the string-tension and fret numbers a player, builder or tech sets an instrument up with. The string-tension endpoint gives the tension a string pulls at pitch from the physics, tension = unit weight × (2 × scale length × frequency)² ÷ 386.4, where the unit weight (lb/in) comes from the string maker's chart — a .010 plain-steel high E on a 25.5-inch scale tuned to 329.6 Hz pulls about 16 lb. The fret-position endpoint gives the distance from the nut to any fret in equal temperament, scale × (1 − 2^(−fret/12)), so the 12th fret sits exactly halfway and the first fret of a 25.5-inch scale is 1.43 inches down — the maths behind every fretboard slot. The set-tension endpoint sums a whole string set into the total load on the neck (a typical six-string runs ~95–120 lb), the number that decides whether a gauge or tuning change needs a truss-rod re-setup. Everything is computed locally and deterministically, so it is instant and private. Ideal for luthier and guitar-tech apps, string-tension and fret-slotting calculators, setup and re-string tools, and music-gear sites. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 compute endpoints. Get unit weights from the string maker's chart. For note↔frequency conversion use a music-theory API.

api.oanor.com/guitar-api

Fretted-instrument lutherie maths as an API, computed locally and deterministically — the fret positions a guitar, bass, mandolin or ukulele builder slots a fingerboard to. This is instrument-building geometry, not music theory. The positions endpoint lays out a whole fingerboard from the scale length using the twelve-tone equal-temperament rule: the distance from the nut to fret n = scale length × (1 − 1 ÷ 2^(n/12)), so the 12th fret lands at exactly half the scale (the octave) and each gap shrinks by the constant ratio 2^(1/12) ≈ 1.0595 toward the bridge — a 25.5-inch Fender scale puts fret 1 at 1.431 inches and fret 12 at 12.75. The fret endpoint gives one fret’s distance from the nut, from the previous fret and to the bridge; the scalelength endpoint runs it backwards, recovering the scale length from a measured distance to a known fret (measure to the 12th and double it). It works in inches or millimetres — 25.5 Fender, 24.75 Gibson, 25.4 classical, 34 bass. Everything is computed locally and deterministically, so it is instant and private. Ideal for lutherie, guitar-building, instrument-design and maker app developers, fingerboard-slotting and fret-calculator tools, and CAD/CNC templates. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 compute endpoints. For note names or frequencies use a music-theory API.

api.oanor.com/fretspacing-api