The air-to-cloth ratio is the volumetric flow rate of air (m³/minute; SI m³/second) flowing through a dust collector's inlet duct divided by the total cloth area (m²) in the filters. The result is expressed in units of velocity.

${\displaystyle v={V/\Delta t \over {A}}}$

The air-to-cloth ratio is typically between 1.5 and 3.5 metres per minute, mainly depending on the concentration of dust loading.

• Details on how to calculate air-to-cloth ratio