Our calculation method

Start with your measurements

Length, area and volume are not interchangeable. Each field shows its unit. Calculators reject impossible values, including openings larger than the walls or a strip longer than the roll.

Keep assumptions visible

Paint coverage, fabric width and box coverage come from your chosen product. The initial values illustrate a calculation; they are not a recommendation for every product.

Round at the right stage

The theoretical requirement is calculated before rounding up to whole tins, bags or rolls. Displayed results are rounded for readability without changing the numbers used in the calculation.

A chosen allowance, not a universal rule

The allowance depends on cuts, patterns and the project’s geometry. You can adjust it, and we explain its effect. These tools do not replace an installation plan, a tested sewing pattern or the manufacturer’s documentation.

What we check

The calculation engines are covered by worked cases and boundary-value tests. Methods and references appear on each page. The tools cover quantities and dimensions for decoration; they do not design structures or technical installations.

Report a correction

Keep the calculation’s sharing link and the relevant inputs. The publisher’s contact details are in the legal notice.