Legal
Terms of use
Updated June 2026. By using ductsizecalculator.com you accept these terms. If they don't work for you, please don't use the site.
What this site is
This is a free, browser-based tool that estimates HVAC duct sizes and related quantities for educational and planning purposes. It is offered to the public at no cost and without registration. We may change, pause, or retire any part of it at any time without notice.
Estimates, not professional advice
The figures produced here are engineering estimates based on published standard methods and stated assumptions. They are not a stamped design and are not a substitute for an ACCA Manual D calculation, a licensed mechanical engineer, the current ASHRAE Handbook of Fundamentals, or your local mechanical code. You must independently verify any result before relying on it. The engineering disclaimer explains the assumptions and limits in detail.
No warranty
We offer the tool on an "as-is, as-available" basis and make no promises about it, whether stated or unstated — not about accuracy, not about suitability for a given purpose, and not about uninterrupted uptime. We do not guarantee that the calculations are free of error or right for any specific installation.
Limitation of liability
As far as the law allows, neither Worklifted Technologies nor the people who build it accept liability for loss or damage of any kind — whether direct or indirect, incidental or consequential, and including equipment failure, comfort complaints, rework, or financial loss — arising from the use of, or inability to use, this site or its results. Any use of the tool is at your own risk.
Acceptable use and intellectual property
Do not attempt to disrupt the site, misuse it, or scrape it in a way that degrades service for others. The site's design, text, and original reference content are the property of Worklifted Technologies; the underlying engineering standards belong to their respective publishers and are referenced, not reproduced in full.
Changes to these terms
These terms may change as the site evolves. If you keep using the site after a revision, that counts as accepting the updated terms. The date noted above reflects the current version.