[REPLACE THIS WITH YOUR REAL NAME AND A SENTENCE ABOUT YOURSELF BEFORE PUBLISHING. Google's helpful-content guidance asks who is behind a site, and AdSense review looks for it. A real name and a plain description of your background is enough; it does not need to be a biography.]
Density, yield and conversion figures are printed on the calculator page that uses them, in a data table, with the source named. Coverage is uneven at present: the gravel and topsoil pages name a document, edition and section for each row; the concrete page does not yet, and improving it is the current priority.
Unit conversions are exact: 27 cubic feet to the cubic yard, 35.3147 cubic feet to the cubic metre. Where a figure is a trade convention rather than a measured constant — waste allowances, compaction factors, typical depths — the page says so.
Pages are drafted with AI assistance and then reviewed and fact-checked before publishing. The gravel and topsoil calculators have been through independent adversarial fact-checking, which found and corrected real errors, including a standard that had been cited but never opened and a specification quoted from a superseded edition.
The concrete calculator has NOT yet been through that process. It was written first, before the checking process existed, and an audit has since found errors on it that are being corrected. Until that work is finished this notice stays here, because telling you which pages have been checked is more useful than a blanket claim that they all have.
This disclosure is here because Google's own guidance asks whether the use of automation is self-evident to visitors. It is: this paragraph is the disclosure.
These calculators are estimating tools. They are not structural design, and they do not replace your supplier's own quantity advice or an engineer's specification for anything load-bearing. Check quantities against your supplier before ordering, and check structural requirements against your local building code.
If a figure looks wrong, say so. Corrections with a source get made and the page's data table is updated. The contact address is on the Contact page.