Zone Damper Sizing Calculator

Size zone dampers for proper airflow control and minimal noise

Design airflow for the zone in CFM. This is the maximum airflow the damper must pass when fully open.
CFM
Target air velocity through the damper. Typical: 500-1500 FPM for low noise, up to 2500 FPM for industrial.
FPM
Round dampers are used in round ductwork. Rectangular are used in sheet metal plenums and rectangular ducts.
The pressure drop budget allocated to the damper in the duct system design. Typical: 0.05-0.15 in.wg.
in.wg

Results

Damper Size
Actual VelocityFPM
Pressure Dropin.wg
Cv Value
Recommended Actuator Torquein-lbs
References: SMACNA HVAC Systems Duct Design manual. Damper Cv = CFM / (4005 * sqrt(dP)). Keep face velocity under 1500 FPM for occupied spaces to limit noise.