Transparent by design

How our calculators work

Each calculator has a stable identifier, versioned definition, structured inputs, deterministic calculation function and structured outputs. The page only formats the answer.

Assumptions and units

We show important assumptions on every calculator page. Conversion factors live centrally rather than being copied into page components. Where product yield or real conditions vary, the result is clearly described as a planning estimate.

Validation and rounding

Inputs have practical minimums. Formulas calculate with full numeric values and round for presentation. Purchase quantities such as rolls, packs and bags round up because partial packs are rarely useful.

Review process

Methods are reviewed when product guidance or accepted practice changes. Safety-critical work should always be checked against product instructions or a qualified professional.