Calculators need sources before they need UI.

Calculator review

Published calculators must pass formula review, unit review, numerical cross-checks, and page-context review.

External tools

Vendor and standards-based tools may be recommended when they are more authoritative or maintain proprietary data. Their logic is not copied or reverse engineered.

A listed tool is checked against an official provider page before publication. The last-checked date records that link and relationship review; it is not an independent validation of the provider's calculations, curves, catalog data, availability, or configuration outputs.

External tool links and disclosures are reviewed quarterly, during launch reviews, and when users report broken or stale links. If a provider page moves or cannot be verified, the link should be corrected, marked for review, or removed from the published directory.

Tool order is editorial and based on engineering relevance, official-source confidence, topic fit, and usefulness for input preparation. Sponsored, affiliate, or partner relationships must be disclosed near the relevant tool; no such relationship is recorded for the current pump-selection tools.