Methodology
How calculations are handled
The calculators use explicit units and small, testable formulas. The principles below apply across all six material estimates.
Units and arithmetic
- Inputs are converted to canonical metric units before calculation.
- Conversions use documented constants.
- Intermediate calculations are not rounded.
- Waste is applied once, after the base quantity is calculated.
- Display rounding does not alter the underlying calculation. Whole purchase units, such as bags, tiles, boxes, and sheets, round upward only when needed.
Assumptions and estimates
Bag yields, gravel densities, paint coverage, grout joints, opening deductions, and package quantities are estimating assumptions. Product data and site conditions can differ, so supplier-specific information and project requirements should take precedence.
Permalinks and testing
Share links contain input state only; calculated outputs are never stored in the URL. Calculator engines and URL handling have automated mathematical tests covering formulas, conversions, validation, rounding, and representative boundary cases.