Duct airflow from velocity calculator

Multiply representative mean velocity by free cross-sectional area; a single local velocity may not represent the duct.

Units

Q = v \times A

Calculator

Enter the values you know and leave one box empty. Calculate finds the empty one, the result or any input.

Given

Q = 650 \times 2.4 = 1{,}560

Symbol	Meaning	Unit
$Q$	duct air volume flow	cfm
$v$	representative mean duct velocity	ft/min
$A$	free duct cross-sectional area	ft²

Symbol	Meaning	Unit
$Q$	duct air volume flow	L/s
$v$	representative mean duct velocity	m/s
$A$	free duct cross-sectional area	m²

Results are estimates for study and screening. Check the inputs, units and assumptions before you use them for design, billing or contract decisions.