Unit Conversion Workflow¶

Conversion procedure — instantiates Dimensional Consistency Check

Converts every quantity into one shared unit convention before combining them, keeping the conversion factors and assumptions attached to the result.

Unit Conversion Workflow is the resolution step of the archetype: where a check detects that quantities are on incompatible units, this procedure fixes it by converting everything onto a single agreed convention before anything is combined. Its defining feature is that it is a correction, not a detection — it presupposes a mismatch has been found and does the disciplined work of eliminating it. Two things make it a workflow rather than a one-off multiply: it converts against an explicit reference standard (the target convention everything is brought to), and it preserves the conversion factors and their assumptions alongside the result, so the chain from raw input to converted value stays auditable. Its own quiet trap is that converting units makes numbers combinable without proving they mean the same thing — a conversion is necessary for compatibility but never sufficient for equivalence.

Example¶

A manufacturer integrates a supply chain where legacy drawings are in imperial units and a new overseas partner works in SI. Part tolerances arrive as ±0.005 inches from one plant and ±0.10 millimetres from another, and they will be combined in a single stack-up analysis. The workflow fixes a reference standard first — millimetres — then converts every imperial value against the exact factor (1 inch = 25.4 mm), so ±0.005 in becomes ±0.127 mm and the two tolerances finally live on the same convention.^[1] Only after everything is in millimetres are the values allowed into the stack-up.

Crucially, the workflow keeps the conversion visible: each converted cell records its original value, the factor applied, and the target unit, so a reviewer can trace ±0.127 mm back to ±0.005 in rather than trusting a bare number. And it stops short of over-claiming — putting both tolerances in millimetres makes them addable, but the workflow flags that one was specified at a different temperature, a meaning difference that conversion alone does not erase. The output is a set of quantities on one clean convention, with the full conversion trail attached.

How it works¶

Fix the target convention. Choose the single reference standard — the unit system everything will be brought to — before converting anything, so there is one destination rather than a tangle of pairwise conversions.
Convert against exact factors. Apply the precise, documented conversion factor to each quantity, carrying enough precision that rounding does not accumulate through the chain.
Preserve the trail. Keep the original value, the factor, and the assumption beside each converted number, so the conversion is auditable rather than a silent overwrite.
Flag what conversion does not settle. Note where matched units still hide a meaning difference (a different reference temperature, base year, or measurement condition), since conversion makes quantities combinable, not equivalent.

Tuning parameters¶

Choice of target convention — which unit system everything is brought to. Picking the one most downstream consumers already use minimizes further conversion and error.
Precision carried — how many significant figures survive each conversion. Too few lets rounding accumulate; too many implies false precision the inputs never had.
Conversion-factor sourcing — exact defined factors versus approximate or context-dependent ones (currency rates, temperature-dependent densities). Approximate factors need their date and assumptions recorded.
Trail granularity — how much of the original-value-and-factor chain is retained: every step, or only the final converted value. Fuller trails cost storage but keep the result auditable.

When it helps, and when it misleads¶

Its strength is that it resolves the most common dimensional problem cleanly and reproducibly: bring everything to one convention, keep the receipts, and quantities that could not be combined now can be. It is the natural follow-through whenever a unit check or audit finds a mismatch.

Its dangers are rounding and over-reach. Converting through long chains at low precision lets error accumulate quietly, and approximate factors (exchange rates, densities) carry assumptions that must travel with the number or they silently expire. The subtler misuse is treating conversion as if it also proved meaning — converting nominal and real dollars to the same currency, or two temperatures measured under different conditions, and then adding them as though matched units guaranteed matched constructs. The discipline is to keep the conversion trail auditable, record the assumptions behind inexact factors, and hand off any residual meaning question to a construct-level check rather than assuming conversion closed it.

How it implements the components¶

reference_standard — the target convention everything is converted to is the reference standard the workflow is built around.
correction_rule — applying documented factors to bring quantities onto that standard is the correction it performs once a mismatch is known.
audit_trail — retaining original values, factors, and assumptions beside each converted number is the trail that keeps the conversion reproducible.

It does not detect the mismatch in the first place (that is Unit Check or Spreadsheet Unit Audit), nor settle whether two same-unit quantities share a meaning after conversion (that is Finance / Accounting Unit Check); it executes and records the correction.

Instantiates: Dimensional Consistency Check — the archetype's resolution step, converting mismatched quantities onto one convention rather than merely flagging them.
Consumes: Unit Check or Spreadsheet Unit Audit supplies the detected mismatch this workflow then resolves.
Sibling mechanisms: Unit Check · Model Input / Output Contract · Cross-Scale Transfer Review · Dimensional Analysis Table · Dimensionless Ratio Construction · Engineering Equation Sanity Check · Finance / Accounting Unit Check · Normalized Metric Design · Per-Capita or Per-Unit Conversion · Spreadsheet Unit Audit · Stock / Flow Separation Check

Notes¶

Conversion and detection are deliberately separate mechanisms: Unit Check finds the mismatch, this workflow fixes it. Keeping them apart is what lets a team standardize how conversions are done and recorded — one reference convention, documented factors, an auditable trail — independently of how mismatches are caught, and prevents the common shortcut of silently overwriting a value with no record of what it used to be.

References¶

[1] The factor-label method (dimensional analysis applied to conversion) treats each conversion factor as a ratio equal to one — e.g. (25.4 mm / 1 inch) — so multiplying by it changes the unit without changing the quantity, and the units cancel to confirm the conversion was set up correctly. ↩