Terms of Service

CFM Calculator (the "Company") provides CFM calculators, ventilation and duct sizing tools, air-changes-per-hour reference data, and educational guides on cfmCalculator.net (the "Website") for HVAC installers and contractors, facility managers, indoor growers, students, and DIY homeowners. By accessing or using the Website in any way — running a calculation, reading a guide, or citing a result — you agree to comply with these Terms of Service. If you object to any term or condition here, or to any guideline posted on the Website, your sole and exclusive remedy is to immediately discontinue use of the Website.

We may revise, modify, or replace these Terms of Service at any time at our sole discretion. Changes take effect immediately upon posting to this page, and the latest version is always linked from the Website footer. Because the Website is free and requires no account, posting is deemed sufficient notice. You should review these Terms periodically — particularly before relying on calculator output for a real installation or purchase.

All output from the Website — base and loss-adjusted CFM figures, duct size and velocity recommendations, equivalent duct diameters, noise-band verdicts, fan-size suggestions, and related notes — is provided for informational, planning, and educational purposes only. It is not a manufacturer's technical datasheet, not an engineered ventilation design, not a code compliance determination, and not professional advice of any kind.

The Website does not replace the manufacturer's fan curves and installation manuals, a licensed mechanical engineer, or the mechanical code adopted in your jurisdiction. Ventilation requirements, make-up air provisions, exhaust and fire codes, and energy standards are specified and enforced differently in every jurisdiction, and their application to your specific installation requires evaluation by qualified professionals. Nothing on this Website creates a professional relationship of any kind.

You agree not to post, transmit, or use the Website in any way that:

• Violates any applicable federal, state, provincial, or local law, including the mechanical and building codes adopted where a project will be built
• Attempts to scrape, crawl, mirror, or bulk-download calculator results, ACH tables, velocity charts, or guide content
• Reverse-engineers, decompiles, or extracts the calculation engines — the volume, ACH, duct-loss, equivalent-diameter, and velocity math — for reuse in another product
• Misrepresents calculator output as a manufacturer's published fan curve or a professionally engineered ventilation design
• Infringes any patent, trademark, trade secret, copyright, or other proprietary right of any party
• Uses forged headers, rotating proxies, or false identifiers to disguise the origin of requests to the Website
• Disrupts, overloads, or interferes with the normal operation of the Website or its infrastructure

Unless you receive explicit written permission from the Company, you may not copy, reproduce, resell, or exploit any part of the Website for commercial purposes. Quoting a short result with attribution and a link in a forum post, lesson, or estimate is welcomed; systematic republication is not.

The Website's software, calculation engines, original text, page designs, logos, and graphics are owned by the Company and protected by copyright and other intellectual-property laws.

Fan and duct manufacturers' technical publications, performance curves, product names, and related references belong to their respective publishers. The Website independently implements publicly documented formulas and estimation methods — including the air-changes-per-hour method and the ASHRAE equivalent-diameter equation — and refers to those publications for identification and educational purposes. This Website is not affiliated with, endorsed by, or sponsored by any fan manufacturer, duct supplier, industry body, or standards organization, and calculator output is not a substitute for the official publications. Where precise product data matters, consult the manufacturer's current datasheet for the model you are installing.

Our Privacy Policy explains how the Company collects, uses, and discloses information, and is incorporated into these Terms by reference. In short: the inputs you enter — room dimensions, ceiling height, ACH, duct length, elbow count, safety factor, and unit system — are processed locally in your browser and are not transmitted to or stored on our servers. Use of the Website constitutes acceptance of the Privacy Policy as well as these Terms.

The Website contains references to fan types and products, duct sizes and materials, manufacturers, suppliers, and third-party resources. These references are provided to help you find authoritative sources and are not intended to imply sponsorship, endorsement, or affiliation, or that any trade name, trademark, or logo may be used by you.

Calculator output may be affected by input accuracy, installation-specific conditions such as flex duct, filters, wall caps, and damper settings, and the gap between a fan's free-air rating and its installed performance. If you believe a formula, value, or guide statement is incorrect, contact us with the page URL, your inputs, and the result you expected — we investigate every report and update content to the extent the authoritative sources allow.

The Website is funded by third-party advertising, including Google AdSense. Ads are clearly distinguished from calculator output and editorial content. We do not control, endorse, or warrant advertised products or services, and any dealings between you and an advertiser are solely between you and that advertiser. Advertising cookies and your opt-out choices are described in the Privacy Policy.

The Company may set limitations on your use of the Website, and may modify, suspend, or discontinue the Website — or any part of it — at any time, with or without notice, at its sole discretion.

THE WEBSITE AND ALL CALCULATORS, REFERENCE DATA, AND GUIDES ARE PROVIDED "AS IS" AND "AS AVAILABLE" WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING WARRANTIES OF ACCURACY, MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. YOUR USE IS ENTIRELY AT YOUR OWN RISK.

TO THE MAXIMUM EXTENT PERMITTED BY LAW, IN NO EVENT SHALL THE COMPANY BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, OR CONSEQUENTIAL DAMAGES ARISING FROM YOUR USE OF (OR INABILITY TO USE) THE WEBSITE — INCLUDING DAMAGES FROM UNDERSIZED OR OVERSIZED INSTALLATIONS, MOISTURE OR MOLD DAMAGE, NOISE COMPLAINTS, FAILED INSPECTIONS, PROPERTY DAMAGE, PERSONAL INJURY, LOST PROFITS, OR ERRORS IN AIRFLOW, DUCT SIZE, OR VELOCITY FIGURES. SOME JURISDICTIONS DO NOT ALLOW CERTAIN WARRANTY EXCLUSIONS OR LIABILITY LIMITATIONS, SO SOME OF THE ABOVE MAY NOT APPLY TO YOU.

These Terms of Service shall be governed by the laws of the United States, without regard to conflict-of-laws provisions. You and the Company agree to submit to the personal and exclusive jurisdiction of the courts located within the United States for any dispute arising from these Terms or your use of the Website.

If any provision of these Terms is held invalid or unenforceable by a court of competent jurisdiction, that holding shall not affect the validity or enforceability of the remaining provisions, which continue in full force. The Company's failure to enforce any right or provision shall not constitute a waiver of that right or provision, or of any further rights. These Terms, together with the Privacy Policy and the Disclaimer, constitute the entire agreement between you and the Company regarding the Website and supersede any prior agreements.

If you have questions about these Terms of Service, or need to report a violation of them, reach us via the contact page. We read every message and respond to legitimate inquiries.