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Open Calculator Standard v1

We publish the schema that drives every calculator on this site. Adopt it for your own tools — if you do, let us know and we'll link to you.

{
  "slug": "concrete",
  "name": "Concrete Calculator",
  "inputs": [ { "key": "length", "type": "number", "unit": "ft", "default": 10 }, ... ],
  "formula": "Volume (yd³) = L × W × D ÷ 27",
  "references": [ "ACI 301" ],
  "faqs": [ ... ]
}

Last updated: 2026-06-20