Why this exists.

Most single-plate lug calculators are opaque spreadsheets. They produce a number, they won't tell you which check governs, and they won't tell you whether the number is from a standard or a guess. The result is engineers re-deriving the same mechanics-of-materials identities on the back of a notepad, every project.

This tool does that derivation once, in public, with sources named, assumptions surfaced, out-of-scope rules firing automatically, and a printable report you can actually share. It is explicitly a preliminary-design tool — not a replacement for detailed engineering analysis or FEA.

Every check is a deterministic function of its inputs with a named source reference and a list of assumptions. The code-specific routes — ASME BTH-1-2020, EN 1993-1-8:2005 §3.13 and DNV-ST-N001:2020 §16 — are each activated only once a hand-computed benchmark reproduces the published equation within a stated tolerance. New clauses and families are added the same way.

The app is open to contributions from engineers willing to supply traceable source material. If you are one of those people, get in touch.