Duct Calculator: HVAC Sizing

The digital ductulator. Equal-friction duct sizing in your pocket, no cardboard slide rule. Type in the airflow and get the duct size. Or type in a duct that's already there and find out what it actually carries. Every calculation runs on the device, with no account and nothing to load. Every subscription starts with a free trial, so you can put it through a real job before you pay for anything. After the trial Ductulator needs a subscription, and the tools below are what it unlocks. Cancel anytime in Settings. WHAT YOUR SUBSCRIPTION UNLOCKS SIZE A NEW DUCT - The exact diameter the airflow needs, plus the nearest standard round size - Fix one side of a rectangular duct and get the matching other side - Equivalent round diameter (Huebscher), to cross-check against round runs - Air velocity, flagged when it runs above the residential guide CHECK A DUCT THAT'S ALREADY THERE - Type in a round diameter, or a width and a height - Read back its velocity, its friction rate, and the airflow it will carry - Adequate or undersized, judged against whichever limit binds first THE MATERIAL CHANGES THE ANSWER - Galvanized, duct board or flexible duct, each with its own ASHRAE roughness - Flex needs a full standard size more than metal at the same airflow. Size a flex run as if it were sheet metal and it always goes in over the friction rate it was designed for, by up to double BUILT ON REAL PHYSICS - Darcy-Weisbach with the Colebrook friction factor, solved on the spot. It is the method behind the ASHRAE friction chart and professional ductulators - Standard air, with supply (0.10 in wg/100ft) and return (0.08) defaults built in, or set your own friction rate - A friction rate you enter is yours. Switching between supply and return never overwrites it, because Manual D designs one system to one rate Terms: https://ductulator.vovaluka.com/terms Privacy: https://ductulator.vovaluka.com/privacy