CFM (Cubic Feet Per Minute)
Affiliate link — we may earn a commissionCFM measures airflow volume, the amount of air a dust collector, blower, or vacuum moves per minute. A shop vacuum pulls 100 to 150 CFM. A single-stage dust collector pulls 650 to 1,200 CFM. A table saw needs about 350 CFM at the dust port for effective collection. A miter saw needs 300 to 500 CFM. If your collector's CFM is lower than what the tool port needs, dust escapes into the shop instead of going into the bag. CFM drops as the hose gets longer or narrower. A 4-inch hose loses less CFM over distance than a 2-1/2-inch hose.
Why It Matters
Connecting a dust collector to a tool port doesn't mean it's working. If the CFM at the port is too low, you get the illusion of dust collection while the fine particles still go into the air. Match the collector's CFM to the tool's requirements and keep hose runs short.