About HVAC Duct Calculator

HVAC Duct Calculator is a free, professional-grade tool designed to help HVAC engineers, contractors, and technicians calculate proper ductwork sizing for residential and commercial HVAC systems.

Our calculator uses industry-standard formulas based on ASHRAE guidelines to determine airflow rates, friction losses, velocity, and recommended duct dimensions. Whether you're working with metal or flex ducts, round or rectangular shapes, our tool provides accurate results in seconds.

We built this tool because we believe every HVAC professional should have access to reliable duct sizing calculations without expensive software subscriptions. Our mission is to make HVAC design calculations accessible, accurate, and easy to use.