Pick your machines, enter your duct run, and get a clear CFM target, duct diameter, and layout tips. No guesswork, no forum digging.
Select the machines you want to collect from, then describe your longest duct run. The calculator estimates the CFM you need and suggests a minimum duct diameter.
Measure from the collector to the farthest machine, following the duct path.
Count every elbow, tee, and wye on the longest run.
Gates let you focus airflow on one machine at a time, which can reduce the peak CFM you need.
Two common starting points. Use these as a sanity check or as a template for your own layout.
A single 1.5 to 2 HP collector with a good filter will handle this. Add a blast gate so you can close off unused ports and keep air velocity up.
You do not need to run every machine at once. With blast gates, size for the worst single machine plus losses. A 2 to 3 HP collector with a 6" main line is a solid starting point.
Short notes to help you avoid the usual pitfalls and get better collection with less frustration.
CFM is how much air moves. Static pressure is how hard the fan has to push. Long runs and many bends increase static pressure. A collector that moves 1,000 CFM at zero static may only move 400 CFM in a real duct system. That is why this calculator adds a loss factor.
Open branches steal airflow. If you leave three ports open while running one machine, most air comes through the path of least resistance, not the machine making chips. Gates let you focus the fan where you need it.
Every foot of duct and every bend slows the air. Place the collector near the dustiest machines when you can. Use smooth-wall pipe instead of flex hose for long runs.
A clogged filter can cut airflow by half. Clean or replace filters on schedule. If your collector has a small filter area, expect to clean it more often.
Flex hose is easy to install but creates more friction. Use it for short connections to machines. For main lines, hard pipe with long-radius elbows keeps air moving faster.
If you see dust settling in the duct, chips piling up at the hood, or the filter clogging fast, your system is undersized or leaking. Fix leaks first, then consider a larger collector or better duct layout.
| Machine | Typical CFM | Notes |
|---|---|---|
| Table saw | 300 to 400 | More if no blade guard port |
| Planer | 400 to 600 | High chip volume |
| Jointer | 300 to 400 | Similar to table saw |
| Miter saw | 250 to 350 | Enclosure helps |
| Bandsaw | 300 to 400 | Lower than planer |
| Router table | 250 to 350 | Depends on fence design |
| Drum sander | 350 to 500 | Fine dust needs good flow |
| Lathe | 200 to 300 | Often under-collected |
Most dust collection questions in forums come down to the same problem: people buy a collector that looks big enough on paper, then wonder why it does not pick up chips. The math is not hard, but it is scattered across old posts and manufacturer charts. This calculator puts the key numbers in one place so you can make a better decision before you spend money.
The CFM values are based on common machine specs and woodworking references. They are starting points, not guarantees. Your duct layout, filter condition, and how well your hoods capture dust all matter. Use the results as a guide, then round up and check your actual setup.
Last updated: 2026 · Version 1.0