Guides
In-depth guides on duct design — the reasoning behind the numbers, the trade-offs each decision carries, and what the calculators cannot tell you on their own. Each one links to the tools that do the arithmetic.
How to Use a Ductulator: Reading the Wheel and the NumbersSetting the wheel, reading the windows, and the three mistakes that oversize a duct run.
Equal Friction vs Static Regain: Choosing a Duct Sizing MethodWhat each duct sizing method does to balance, fan energy and first cost — and when to use which.
Duct Aspect Ratio: Why 4:1 Is the LineWhat a flatter duct really costs in metal, insulation, friction and noise — with the numbers.