Duct sizing is important for proper airflow distribution in HVAC systems. Correct duct size ensures balanced airflow, low noise and efficient system operation.
Duct Area = CFM ÷ Velocity
For round ducts:
Diameter = √( (4 × Area) ÷ π )
Airflow = 1000 CFM Velocity = 900 FPM
Recommended duct diameter ≈ 14 inches
This calculator helps HVAC engineers estimate round duct size quickly.
Duct size is calculated using airflow (CFM) and air velocity (FPM) to determine the required duct cross-section area.
Typical recommended duct velocity is between 700–900 FPM for supply ducts.
Correct duct size prevents excessive noise, pressure drop and airflow imbalance.
Small ducts increase air velocity, causing noise, pressure loss and reduced system efficiency.