Duct Sizing Hvac Cfm Chart

Flex duct has a higher pressure drop and as such may require the size shown on this guide be increased by 1 round size for up to 800 cfm and 2 round sizes.

Duct sizing hvac cfm chart. You can also do this by checking for them online or by using a manual that is sold by distributors. To insure proper distribution of air volume dampers must be used for all branch runs. Cfm 4 cfm 6 cfm 8 cfm 10 cfm 12 60 6x4 60 4x6 90 4x8 120 4x10 150 4x12 90 8x4 110 6x6 160 6x8 215 6x10 270 6x12. Larger volumes or higher static pressures should be dealt with on an individual job basis.

Calculate the duct size by using a duct calculator. The chart is based on metal duct. Duct system sizes and airflow quick chart created date. Note also the return air grille sizing formula at the top of the chart.

The chart should not be used to design complete duct systems. If a room is 250 square feet the result will be a duct size of 8 inch round. 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.