Calculation methodology
How the calculators are reviewed
The calculation path is kept separate from page design so formulas can be tested directly and traced by version.
Reviewed formulas
Calculator definitions describe inputs, units, validation, outputs, and presentation. Executable formulas live in allowlisted TypeScript modules, not in page copy or configuration. The browser uses that same reviewed calculation path.
Units and precision
Shared unit utilities normalize measurements before formulas run. Intermediate values are not rounded for display; presentation rounding is applied only when a result is shown.
Tests and versions
Fixed known-answer cases are derived independently from production formula code. Geometry and unit conversions have separate tests. Every result carries calculator, formula, and unit-normalization versions so a past calculation method remains identifiable.
References and updates
Each calculator includes a concise methodology section with its formula, assumptions, limitations, and applicable source material. Formula or reviewed product-data changes receive a new version and new test review.
Calculator-specific methods
Limits
Quantity estimates do not determine structural dimensions, reinforcement, suitability, waste allowance, local code compliance, or the exact yield of every product. Verify critical quantities and specifications before buying materials or beginning work.