How much CFM do I need?

It depends on the largest machine: table saw needs ~350 CFM at the port, thicknesser ~500 CFM, and wide planers ~800 CFM. For a home workshop running one machine at a time, size for the largest machine.

What duct diameter should I use?

Main duct should be at least 100mm (4") for most home workshops. Use 125mm (5") if you have a thicknesser or large planer. Never reduce below the machine port size as this restricts airflow.

Is a single-stage or two-stage collector better?

Two-stage collectors (with a cyclone separator) are much better. They capture 99% of dust before it reaches the filter, extending filter life and improving suction. Single-stage collectors clog filters quickly.

WoodCalcs

Dust Collection Calculator — Workshop Extraction

Calculate CFM requirements and duct sizing for workshop dust extraction.

Largest Dust Port

Total Duct Length

How We Calculate This

CFM requirements are based on the dust port size of the largest machine. The system must maintain adequate air velocity (typically 4000 feet per minute in the main duct) to transport dust.

Static pressure loss ≈ 0.5 inches WC per 3 metres of duct

Frequently Asked Questions

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Last updated: February 2026

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