Reference
The calculators publish figures the industry usually keeps to itself. These pages show where those figures came from, what they are calibrated against, and where the model stops being trustworthy.
The vocabulary a manufacturer will use with you, defined so the first sentence is a complete answer — including the pairs people routinely mix up.
Read the terms →The full baseline table, the sensitivity coefficients behind every calculator, the published figures they are calibrated to, and a candid list of what the model cannot do.
See the methodology →Provenance and limitations for the 50-metro design load dataset, and how to get authoritative values instead.
Read the provenance →Why publish the method at all? A steel weight per square foot with no derivation is just a claim. Showing the working is what makes it possible to argue with, and a figure you can argue with is worth more than one you cannot.