Terms of Service & Disclaimer
By using DuctPro Max you agree to these terms. They explain what the tools are for and, importantly, what they are not for.
All calculator results, cost estimates, project plans and guides on DuctPro Max are provided for preliminary estimation purposes only. They are approximations based on published methods and representative assumptions — not stamped engineering design, code-approved documentation, equipment selection or construction documents. Final duct sizing, construction and installation must be performed by qualified professionals and must comply with the applicable codes and standards for your project.
No professional engineering service
DuctPro Max is an educational and estimating tool. Using it does not create an engineer–client relationship, and nothing produced by the site is a professional certification, engineering seal, permit document or specification. A licensed professional must verify every result before it is used on a drawing, submittal, bid or installed system.
Accuracy of results
The calculators use recognized methods — Darcy–Weisbach friction with the Altshul–Tsal friction-factor approximation, fitting loss coefficients based on the ASHRAE Handbook—Fundamentals, and equivalent-diameter conversions — with simplified, representative assumptions. Real systems differ: actual fitting geometry, leakage, loads, equipment losses, altitude, materials and field conditions all change real outcomes. Results may therefore differ from measured performance, sometimes significantly.
Your responsibility
You are responsible for checking inputs, interpreting results, confirming them against the actual project, and complying with all applicable codes, standards, permits and safety requirements. Never rely solely on a calculator output for a safety-related decision, including fire and smoke control, hospital and laboratory systems, or combustion exhaust.
Limitation of liability
DuctPro Max is provided “as is” without warranties of any kind, express or implied, including accuracy, fitness for a particular purpose or non-infringement. To the maximum extent permitted by law, the DuctPro Max team is not liable for any direct, indirect, incidental or consequential loss arising from the use of, or inability to use, the site or its results — including construction costs, rework, equipment damage or personal injury.
Acceptable use
You may use the tools and read the guides freely, including for your own projects and bids. You may not scrape, resell, republish the site's content as your own, or submit false, abusive or automated entries through its forms. We may remove submitted content and block misuse at our discretion.
Third-party content and ads
The site displays advertising and links to third-party resources, such as code publishers and contractor listings. Contractor entries are submitted by users and are not verified or endorsed by DuctPro Max; you are responsible for checking any contractor before hiring. We are not responsible for third-party content, pricing or privacy practices.
Changes to these terms
We may update these terms as tools and policies change. Material changes are noted on the Updates page. Continued use of the site after a change means you accept the updated terms.
Contact
Questions about these terms can be sent through the Contact page.