About

About DATUM

Who made these, why they exist, and what they are not.

Who. DATUM is written by a practising architect in New York. Every calculator here is one I use, or one I got tired of not being able to trust. No employer, client or project is represented on this site. The work here is mine and separate from it.

Why. Search for any construction calculator and you get a dozen near-identical pages. They give you a number to seven decimal places, cite nothing, and stop. That is fine until the number matters. A stair can be arithmetically perfect and still fail inspection. A concrete order can be correct and still leave you short at the far end of a pour. Those are the cases this site is built for.

How the numbers are checked. Every constant that comes from a source names it; the ones that are rules of thumb say so on the page. Bag yields cite the manufacturer's technical data sheet number. Code limits cite the section number. Unit conversions use exact legal definitions rather than rounded factors: 1 pyeong is 400/121 m², 1 ft² is 0.09290304 m². If a number appears here, you can go and check it against the source.

How they are maintained. Building codes get amended and manufacturers change their products. A calculator running on a superseded code is worse than no calculator, so the sourced constants sit in a manifest, and a build fails if the code drifts from it. That catches a silent edit; it does not re-read a standard that has since been revised.

Every page is run before it ships. Before any version of this site goes live, every calculator is loaded in a real browser and its worked example is recomputed and compared, cell by cell, with the number printed on the page. The last full run was on 2026-10-29: 2,808 values across 228 calculators, every one matching. A page whose example disagrees with its own widget does not ship. The same run checks that each translated page is the same program as its English original — the arithmetic, the option values and the order of every output are compared token for token — so a Korean or Spanish page cannot drift from the one it was translated from.

Why there are other languages. The calculators exist in other languages because the units do. A reader in Seoul prices an apartment by the pyeong, a farmer in Colombia measures by the fanegada, a builder in Istanbul buys land by the dönüm — and the English pages cannot answer those questions. Each language section is written for its own units, its own paperwork and its own decimal notation, with the same sources and the same checks as the English pages. A translation adds nothing the source did not say; a page about a local unit is written from a read source for that unit, and says which. Pages that have not yet earned a place in search are kept out of the index until they do.

Your inputs stay in your browser. Every calculator here runs entirely as JavaScript on the page you are looking at. Nothing you type is transmitted, logged or stored anywhere. There is no account, no form and no database behind any of it.

What this is not. These are design aids, not compliance certifications and not professional advice. Building codes are amended by state and local jurisdiction; confirm the adopted edition and any local amendment with the authority having jurisdiction before relying on anything here. Manufacturer figures vary by product, so check the bag, the box or the data sheet you actually have. For anything that carries real consequence, have it reviewed by the licensed professional responsible for the work.

Corrections. If a number here is wrong, or a cited constant no longer matches its source, write to corrections@formgiving.ai. A calculator that quietly disagrees with the standard it claims to follow is worse than no calculator, so corrections get priority over new pages.