Methodology

Start with explicit inputs

Every calculation begins with values a user can see and edit. Product coverage, labor hours, transfer efficiency, prices, ratios, and package data are blank by default. The Use example control loads demonstration values only after the user asks for them.

Calculate consistently and round last

To keep metric and US customary results equivalent, the calculators convert entered values to a consistent set of units before doing the arithmetic. They keep full precision during the calculation and round only the displayed result. Money is handled in cents to avoid rounding drift.

Separate physical quantity from purchase quantity

The wrap tool distinguishes net geometric area, handling allowance, waste, packing loss, and rounded purchase units. The paint tool distinguishes sprayable quantity, ratio components, package quantity, and leftover. The panel cost tool distinguishes direct labor and materials from fees, overhead, contingency, and optional tax.

Keep uncertainty explainable

Wrap ranges change one named surface factor. Paint stages remain separate instead of blending unlike coverage assumptions. Panel-cost ranges require three explicit scenarios rather than a hidden percentage. Warnings identify factors that the model does not represent.

Version and review

Each result includes method version 1 so printed and shared estimates can be tied to the method that produced them. The version changes only when the meaning of a calculation changes. Explanations and worked examples are kept in step with the calculators and checked against known results. Demonstration assumptions are modeling choices, not manufacturer data or professional standards. Replace them with project-specific measurements, product data, and written rates before relying on a result.