Air Duct Velocity calculator

SI Units

air volume (m3/s)
diameter (m)

or alternatively

side length - a (m)
side length - b (m)

Imperial Units

air volume (cfm)
diameter (in)

or alternatively

side length - a (in)
side length - b (in)

Air Duct Velocity formula

vi = qi / Ai

    = 576 qi / (π di2)

    = 144 qi / (ai bi)         (1)

where Ai = area of duct (square feet), qi = air flow (cfm), vi = air velocity (ft/min), di = diameter of duct (inches), bi = width of duct (inches), ai = width of duct (inches)