Duct Size Calculator Online

Introduction: Efficient duct sizing is paramount for maintaining optimal airflow in HVAC systems, ensuring peak performance and energy efficiency. The Online Duct Size Calculator, tailored for airflow and velocity considerations, provides personalized recommendations to assist HVAC professionals and enthusiasts in selecting the ideal duct size. By incorporating the required airflow in cubic feet per minute (CFM) and desired velocity, this online tool aids users in achieving effective ventilation and climate control.

Formula: The calculator employs the airflow in CFM and velocity parameters to calculate the recommended duct size. This calculation involves dividing the airflow by the velocity, resulting in a duct size that maintains the desired airflow velocity for efficient ventilation.

How to Use:

  1. Enter the required airflow in cubic feet per minute (CFM).
  2. Enter the desired velocity in feet per minute.
  3. Click the “Calculate” button to obtain the recommended duct size in square inches.

Example: For instance, if the required airflow is 1200 CFM and the desired velocity is 400 feet per minute, the online calculator will instantly calculate and display the recommended duct size.


  1. Q: Is the Online Duct Size Calculator suitable for residential HVAC systems? A: Yes, the online calculator is applicable to both residential and commercial HVAC systems, providing recommendations based on airflow and velocity in CFM.
  2. Q: How accurate is the calculator in determining duct size for varying CFM values? A: The accuracy of the calculator depends on precise inputs for airflow and velocity. Ensure accurate values for optimal sizing recommendations.
  3. Q: Can the online tool be customized for specific HVAC system types and applications? A: The online calculator is designed to accommodate various HVAC system types, including forced air and ventilation systems, based on CFM requirements.
  4. Q: Is the tool accessible on different devices and web browsers? A: Yes, the online calculator is accessible on various devices and web browsers, providing convenience for users.
  5. Q: How often should the online calculator be updated for accurate recommendations? A: The online calculator is regularly updated to ensure accurate recommendations based on current airflow and velocity parameters.

Conclusion: The Online Duct Size Calculator, rooted in airflow and velocity considerations, serves as a valuable tool for HVAC professionals and enthusiasts seeking efficient ventilation solutions. While it provides recommendations based on airflow, velocity, and sizing logic, it is advisable to consult with HVAC experts for site-specific advice and adherence to industry standards. Utilize this online calculator as a convenient solution for planning ductwork, contributing to enhanced HVAC system performance and energy efficiency.

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