Credits and licences

Last updated 2026-10-11

Our own code

The tools and page layouts are written for this site. The pages make no requests to other servers.

Formulas and sources

The calculators use plain geometry and arithmetic in our own code. Where a default comes from a published source, the page names it: concrete bag yields printed by the manufacturers (for example Quikrete and Sakrete), the 4-inch sphere opening rule and guard rules of the International Residential Code (section numbers given; the code text is not reproduced), and the DORI pixel densities of IEC 62676-4. Prices are always typed by you.

Third-party material

None. No third-party libraries, fonts or data sets are used.