How we build our calculators

You use these numbers to buy materials, so we treat them seriously.

Formulas are code, and the code is tested

Every calculator runs on the same small calculation library. Each formula has automated tests against known, published values, for example the number of pre-mixed concrete bags in a cubic yard. A page cannot be published if any test fails.

Material numbers come from sources

Bag yields, densities and recommended depths come from manufacturers, university extension services, standards bodies and trade associations. Each page lists the sources it relies on. Numbers in our text are inserted from that sourced data, not typed by hand, so the text and the calculator always agree.

AI-assisted writing, human review

We use AI tools to help draft the explanations on our pages. Drafts are checked automatically for numbers without a source and for duplicated text, and then reviewed by an editor before they go live. The review date is shown at the bottom of each page.

Estimates, not engineering

Our results are estimates for planning and buying materials. They are not structural engineering advice. Check local building codes and the label of the product you buy, and ask a professional for structural work.

Corrections

If you find an error, tell us through the contact details on the About page. We fix confirmed errors and update the page date.

Maintained by FigureYard editorial team.