How to Choose a Wood Shop Vacuum System: Sizing, CFM, and Static Pressure Explained

Match airflow at the tool, hose bore, filter area, and bag capacity to your biggest machine; a shop vacuum’s headline CFM hides all four.

A shop vacuum that leaves a gray film on the bench is rarely underpowered; it is usually mismatched. Four published numbers decide how to choose a wood shop vacuum system: airflow in cubic feet per minute, static pressure in inches of water lift, filter area, and container volume. Read them together and the guesswork disappears.

The reason is resistance. Every foot of hose, every 90-degree bend, every adapter step-down, and every loaded filter eats into the pull a vacuum can generate. Below is how the numbers relate, which ones to compare against each other, and where a portable extractor stops being enough.

What Do CFM And Static Pressure Actually Measure?

CFM measures air volume moved per minute, while static pressure — quoted as inches of water lift — measures the pull available to move that air against resistance. Volume without pull stalls in a narrow hose, and pull without volume cannot clear a wide planer chute.

Festool lists its current US CT extractors at 130 to 138 CFM and 96 inches of static water lift, from the 3.96-gallon CT 15 up to the 12.7-gallon CT 48. Those ratings are taken at the extractor; the tool end sees less once a hose, bag, and filter sit in the path.

Three habits cause most of the shortfall:

• Buying by motor wattage instead of published airflow and water lift.
• Comparing a free-air CFM figure to a rating taken through a full hose and filter.
• Adding long hoses, sharp bends, and undersized adapters without counting the pressure loss they bring.

Where a tool maker publishes an airflow requirement, that figure is the one to meet. The extractor’s free-air CFM is not a substitute for it.

Sizing A Wood Shop Vacuum System: What Decides The Outcome

The largest tool you own sets the requirement, and the hose, filter, and bag either meet it or choke it. Sizing runs from the tool port back to the extractor, never the other way around.

1. Start at the biggest port. Note the port size on your largest machine and any airflow figure the tool maker publishes.
2. Match the hose to the port. A narrow hose raises resistance and rewards higher static pressure; an oversized hose on a small port can drop capture velocity.
3. Compare CFM and lift together. One figure alone says nothing about how the pair behaves with a bag in place.
4. Add filter area for fine dust. Drywall sanding and long sanding sessions cake a filter fast, so Festool builds AutoClean versions — the CT 36 EI AC and CT 48 EI AC — for that caking dust.
5. Size the container to the job. Bigger bags mean fewer emptying stops, more weight, and more floor space.
6. Plan for chips. A cyclone pre-separator keeps the main filter clean, though its extra fittings and hose count against airflow.

Every current US Festool CT model runs on 120 VAC and lists 96 inches of water lift; the cordless CTC MIDI is the exception at 76 inches.

Festool’s construction-site dust extractors page puts each model’s airflow, lift, and tank size side by side, which makes it plain how little airflow changes between a 4-gallon unit and a 12.7-gallon one.

Which Tools Outgrow A Portable Dust Extractor?

Portable extractors suit one connected power tool, cleanup, and work that moves around the shop. Stationary jointers, planers, wide-belt sanders, long duct runs, and multi-branch systems need a larger collector or cyclone, because chip volume and duct length drive that call.

Two limits are worth checking before you buy. Cordless extraction runs short — Festool rates the CTC MIDI at 12 to 22 minutes on two 4.0 Ah packs and 16 to 30 minutes on two 5.2 Ah packs. Wet pickup is the other: applicable MIDI models need the specified wet filter, and Festool’s CT documentation describes a LevelStop motor shutoff when water reaches the limit.

HEPA filtration captures what the bag lets through. It does not replace source capture, a well-fitted bag, or a respirator for fine dust.

If comparing machines beats reading spec sheets, these tested wood shop vacuum system picks line up the models with the numbers above in view.

Before checkout, confirm four things: the port size on your largest tool, the hose bore that fits it, filter area that matches your dust, and a bag that lasts a full session. Those answers choose the machine.