How many CFM do I need for dust extraction?

The CFM requirement depends on your primary machine. At a 4" (100mm) port a benchtop planer/thicknesser needs ~400 CFM, a table saw ~350 CFM, and a router table ~195 CFM. Full-size floor-standing machines on a 6" (150mm) port draw far more — a 15-20" planer wants ~750-800 CFM. Size your system for the most demanding machine plus 20% margin.

What pipe diameter should I use for dust extraction?

Main ducts are typically 100-150mm. Branch runs to individual machines use 100mm for table saws and planers, 65mm for routers and small sanders. The main duct must be large enough to carry the full air volume at 20 m/s transport velocity.

Do I need a blast gate for each machine?

Yes. Blast gates close off branch pipes to machines not in use, concentrating suction at the active machine. Without blast gates, air flow is split between all branches, reducing effectiveness at each machine.

What transport velocity do I need in dust extraction pipes?

A minimum of 20 m/s (4000 ft/min) is recommended for wood dust to prevent particles settling in the pipes. Fine dust from sanders may need slightly less, but coarser chips from planers need the full 20 m/s.

WoodCalcs

Dust Extraction Calculator — Workshop Sizing

Size your dust extraction system. Calculate CFM, pipe diameter, static pressure, and filter requirements.

Number of Machines

Total machines connected

Main Pipe Run Length

Total length of the main duct run (m)

Number of 90° Bends

Primary MachineMost demanding machine

How We Calculate This

This calculator sizes a dust extraction system based on your workshop machines, pipe layout, and the primary machine's CFM requirement.

Key calculations

CFM: Based on the primary machine plus 20% margin
Pipe diameter: Calculated from CFM and transport velocity (default 20 m/s)
Static pressure: Sum of pipe friction (~3 Pa per metre), bend losses, and fixed machine entry + filter loss
Each 90° bend: Adds ~20 Pa in small-bore round duct
Filter area: Minimum 1 m² per 1000 CFM (indicative)

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Always verify measurements and material quantities before cutting or purchasing.