How we compute — sources & code editions
CrewCalcs is built to be trusted on the jobsite. Here is exactly how the numbers are produced, where they come from, and how we keep them right.
We compute, we don't copy
Every result comes from a published method or equation, not from reprinting a code table. Where a small factual table is genuinely needed (a correction factor, a fixture-unit value), we reformat the minimum necessary and cite it by section number and edition. We never republish code text, table titles, or notes verbatim.
Code editions
Each value derived from a code shows the edition it came from (for example "NEC 2023", "IRC 2021", "IPC 2021"). Codes are adopted — and amended — locally, so the edition your Authority Having Jurisdiction (AHJ) enforces may differ. Always confirm against your adopted edition.
Physical properties
Thermodynamic and geometric properties (refrigerant saturation curves, air psychrometrics, pipe and duct dimensions, steel section properties) are physical facts. We generate them from open sources such as CoolProp and ASHRAE standard formulas, or from manufacturer and standards data, and we validate them against published anchor values.
Estimator assumptions
Some tools (for example the HVAC load estimator) rely on engineering assumptions — envelope U-values by construction vintage, air densities, diversity factors. These are documented on each tool and are defensible planning defaults, not code requirements. Advanced fields let professionals override them.
Anchor tests
Every calculation engine is unit-tested against published anchor values, not against itself. If a tool cannot reproduce the published number within the stated tolerance, it does not ship. This is how we keep the math honest.
Editorial standards
Our guides are written and signed by the CrewCalcs editorial team, not by invented individuals — we don't manufacture author names or credentials. The credibility is meant to come from the work you can check: every guide is built to a cited US code edition, every number is validated against published values and shown step by step, and each article carries the date it was last reviewed and the standard it was reviewed against.
Correction policy
Found a number that looks off? Tell us. We treat correctness as the product. We fix confirmed errors quickly, note the code section and source we verified against, and re-run the anchor tests before republishing.