Size ductwork based on CFM requirements and velocity
Our ductwork sizing calculator determines the proper duct dimensions based on required airflow (CFM) and maximum velocity. Properly sized ducts deliver conditioned air efficiently without excessive noise, while undersized ducts create airflow problems and increase energy costs.
The calculator offers both round and rectangular duct options and matches your CFM requirements to standard duct sizes. It calculates the actual air velocity and provides noise level guidance - residential systems should keep velocity below 900 FPM for quiet operation.
This tool is valuable for HVAC installers, homeowners adding runs to existing systems, and anyone asking "what size duct do I need?" or "how do I size HVAC ducts?" Proper duct sizing ensures your HVAC system performs as designed and maintains comfort throughout your home.
Follow these steps to size your ductwork: