Tensora: String Tension

A fully offline string-tension calculator for guitar and bass. Version 1.5 adds Setup Risk Brief, a luthier-style preflight that flags uneven string tension, overly slack or tight strings, and interpolated gauge estimates before you commit to a set.

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Setup Risk Brief (new in 1.5)

The calculator now grades the active setup with a compact preflight score. It checks tension spread, per-string comfort bands, exact versus interpolated unit-weight data, and produces practical notes such as lighter/heavier gauge suggestions.

Flatwound and construction data

Tensora includes plain steel, nickel wound, stainless wound, flat wound, phosphor bronze, bass nickel roundwound, and bass flat wound reference data, with guides explaining how construction changes unit weight and feel.

Setup Comparison

The Compare tab puts your current setup (A) next to any saved setup (B). See per-string tension deltas, total pull difference, average per-string tension, and spread — all at a glance. Perfect for checking whether a gauge change on one guitar matches the feel of another, or comparing a roundwound set against a flatwound equivalent.

Core features

Tension calculator for electric (6/7/8-string), acoustic, and bass (4/5/6-string)
Multiscale / fanned-fret support with per-string scale interpolation
Finder: gauge-for-target-tension and balanced-set builder
Large tuning library (drop, baritone, open, extended-range, bass)
Seven construction types: plain steel, nickel wound, stainless wound, flat wound, phosphor bronze, bass nickel roundwound, bass flat wound
Illustrated guides, unit-weight tables, note frequency table, glossary
Fully offline — no account, no ads, no developer server

What's New in 1.5

Setup Risk Brief — a new calculator card that scores the active setup and flags tuning/gauge issues
Comfort-band checks — see whether strings fall below or above the expected feel band for the instrument class
Spread warnings — catch large per-string tension differences before saving or sharing the setup
Gauge data notes — interpolated estimates are clearly called out when exact unit-weight anchors are not available

Last updated: June 28, 2026

Previous version highlights

Compare tab — side-by-side tension comparison between any two saved setups
Share button — export a complete formatted tension summary via the iOS share sheet
Stainless wound — electric guitar stainless roundwound construction type
Tuning Range view — per-string safe-tension envelope chart showing how far you can drop or raise each string

How tension is calculated

Tensora uses the standard string physics formula: T = UW × (2 × L × F)² ÷ 386.4, where UW is unit weight (lb/in), L is scale length (in), and F is frequency (Hz). Unit weights come from published D'Addario data for plain steel and nickel wound; phosphor bronze, bass nickel, flat wound (electric and bass) are back-calculated from published per-string tensions; stainless wound uses the steel/nickel density ratio (≈ 1.065×). All figures are reference estimates; real strings vary by brand ≈±3.5%.