Standard Tier Module
Unit Conversion Engine with Precision Chain
Convert units on exact defined SI factors, and see exactly how much rounding a multi-hop chain added.
See it run - a worked example, 100% in this browser tab
The problem
Unit conversions silently mix incompatible definitions (survey vs international foot, US vs imperial gallon, thermochemical vs IT calorie) and accumulate rounding across multi-step chains, leaving teams unsure which factor produced a figure.
The local-first solution
This converter computes length, mass, volume, area, time, energy, pressure, and speed on exact DEFINED SI / NIST factors plus an exact affine temperature map, names the factor it used, and runs a chained conversion through the real GeoNum kernel to report the drift the multi-hop path added versus the single-factor result. All client-side, nothing uploaded.
What it does
Length / mass / volume / area / time / energy / pressure / speed conversions on defined factors
Exact affine C / F / K temperature conversion (never routed through the ratio chain)
Direct single-factor result alongside a hop-by-hop chained result
Drift between the two paths (absolute and relative) plus the GeoNum drift flagged across the chain
Explicitly names the exact factor used so a wrong variant cannot silently mis-convert
GeoNum-tracked verdict on the chain with an honest untracked fallback
Honest scope
All factors are DEFINED values or exact decimal/integer ratios and the arithmetic over them is exact f64. Distinct definitions (survey vs international foot, US vs imperial gallon, thermochemical vs IT calorie, Troy vs avoirdupois ounce) are confirmable inputs - the plugin names the one it used. NOT modeled: non-linear scales (decibel, pH, Richter), currency, and time-zone/calendar offsets. GeoNum is an uncertainty signal, not extra precision.
Authorities cited
- BIPM, The International System of Units (SI Brochure), 9th edition (2019). Defines the metre, kilogram, second, kelvin and the 2019 fixed constants (elementary charge -> exact eV).
- NIST Special Publication 811:2008, Guide for the Use of the International System of Units (SI), B.G. Taylor & A. Thompson, App. B.8 (factors for units accepted/used with the SI).
- International Yard and Pound Agreement (1959): 1 yard = 0.9144 m exactly, 1 avoirdupois pound = 0.45359237 kg exactly -> 1 inch = 25.4 mm and 1 ft = 0.3048 m exactly.
- NIST SP 811 App. B.8: US liquid gallon = 231 cubic inches exactly = 3.785411784 L; US fluid ounce = gallon/128.
- NIST SP 811: thermochemical calorie = 4.184 J exactly; kilowatt-hour = 3.6e6 J exactly; standard atmosphere = 101,325 Pa exactly; standard gravity g0 = 9.80665 m/s^2 exactly (used for lbf -> psi).
- ITS-90 / SI Brochure: thermodynamic temperature relations T/K = t/C + 273.15; t/F = (9/5) t/C + 32; Rankine T/R = (9/5) T/K (affine, not a ratio).
- GeoNum v2.2 (GDBS substrate, /js/geo-num.js): drift compartment as a conditioning-based uncertainty signal under the conditional stability theorem (drift thresholds: <1 PRECISE, <SHADES/10 VALID, <SHADES/2 DEGRADED).
Convert with the factor named
Run conversions in your browser with nothing uploaded, then route the named-factor results and chain-drift report into a Sandbox workspace or attach them to a Worklog case.