Ductwork Calculator
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How to size HVAC ductwork
This tool converts your system tonnage into required airflow (CFM) and suggests main trunk, return, and branch duct sizing. It is planning guidance; a contractor should verify with a Manual D duct design.
Frequently asked questions
How many CFM per ton of AC?
About 400 CFM per ton is standard, though 350 to 450 is used depending on humidity and equipment. The calculator lets you choose the CFM-per-ton figure.
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