Quote Cart
Airflow Calculator
Calculate the airflow through a duct from the air velocity and duct cross-sectional dimensions. Get results in both m³/h and CFM.
How to Calculate Airflow
Airflow (m³/h) = Velocity (m/s) × Area (m²) × 3600. For a rectangular duct, the area is simply width × height. For circular ducts, use π × r².
This calculation is fundamental for verifying that a duct can deliver the required airflow for a room or zone.
Frequently Asked Questions
How do I calculate airflow in CFM?
First calculate airflow in m³/h (Velocity × Area × 3600), then divide by 1.699 to convert to CFM. Or: CFM = Velocity (m/s) × Area (m²) × 2118.9.
What is a good air velocity in ducts?
Residential: 2–5 m/s. Commercial: 5–8 m/s. High-velocity systems: 8–12 m/s. Higher velocities increase noise and pressure drop.
Airflow Calculator
Related Airflow & Ventilation Tools
Duct Size Calculator
Calculate duct diameter or rectangular dimensions from airflow and velocity.
CFM to m³/h Converter
Convert Cubic Feet per Minute to cubic metres per hour.
L/s to m³/h Converter
Convert Litres per Second to cubic metres per hour.
Air Changes per Hour Calculator
Calculate how many times the air in a room is fully replaced per hour.
Need Professional Help?
Post a request and get competing quotes from rated HVAC engineers nationwide.