Sizing

Air filter CFM for a 32x24 three-car garage shop

A 32 x 24 x 9 ft garage holds 6,912 cubic feet, so 6 air changes per hour takes 691 CFM: 2 Grizzly G0738 on its 409 CFM speed. At 10 air changes it takes 1,152 CFM, or 3 units.

By the GarageShopCalc editors · Updated 2026-10-13 · Researched from manufacturer specifications, code tables and verified owner reviews

CFM and units by air-change target

Hanging air filters for 6,912 cu ft
Target	CFM needed	G0738 at 260 CFM	at 362 CFM	at 409 CFM
6 air changes per hour	691	3	2	2
8 air changes per hour	922	4	3	3
10 air changes per hour	1,152	5	4	3

Air changes per hour = CFM x 60 / room volume. The G0738 speeds (260, 362 and 409 CFM) are the figures on the grizzly.com listing. At full speed one unit gives 3.6 air changes per hour in this garage. A filter polishes the air after the collector has done its job; it does not replace capture at the machine, and a respirator is still the thing between you and the dust you cannot see.

Hang it where it can circulate the room, near the table saw side and away from the collector exhaust, and set the timer so it keeps running after you stop cutting.

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Amazon and Grizzly, side by side

Each card shows an Amazon pick and a Grizzly Industrial pick for the same job.

Hanging air filter

POWERTEC AF4001E 3-Speed RF Remote Controlled Air Filtration See on Amazon

Grizzly G0738 3-Speed Hanging Air Filter Buy direct at Grizzly

Both are 3-speed ceiling-hung filters in the 300 to 400 CFM class with remotes. The Grizzly unit is owner-rated 4.8 on grizzly.com across 301 reviews.

Prices change often and Grizzly runs sales, so the buttons show current prices.

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Air filtration by garage size: the other answers

Frequently asked questions

How many air changes per hour does a 32x24 three-car shop need?

Six is a common shop convention for light dust and ten for heavy sanding days. For 6,912 cubic feet that is 691 to 1,152 CFM.

This page is researched guidance, not professional electrical, engineering or safety advice. Circuits, loads and clearances depend on your house, your service and your town: have a licensed electrician confirm any wiring, and check local code and each manufacturer's manual before you act.