Duct Size Chart
Larger volumes or higher static pressures should be dealt with on an individual job basis.
Duct size chart. Air volume equivalent round air volume cfm 4 6 8 10 12 duct inches cfm 50 6 x 4 550 75 6 x 4 675 100 8 x 4 6 x 6 6 100 125 10 x 4 6 x 6 7 125. If desired airflow exceeds the cfm rating increase to the next duct size 4. Flex duct 05 on most metal duct calculator round metal pipe 06 on most metal duct calculators field duct sizing chart rectangular sheet metal duct 07 on most metal duct calculators.
How to use duct chart. While a duct sizing calculator built for a specific type of ductwork is the best possible method for sizing ducts the attached chart can be used in most single story homes with a centrally located unit and reasonable length duct runs. Field duct sizing chart rectangular sheet metal duct 07 on most metal duct calculators step one identify the volume of air that will be passing through the duct step two select the duct size from the table that can carry that volume of air step three if desired airflow exceeds the cfm rating increase to the next duct size.
This equal friction method of duct sizing should be adequate for normal residential furnace heating and air conditioning applications. Listed cfm is based on typical field results and may vary install dampers 5.