HDDuctDesigner V9.5 Duct Sizing & Fitting Pressure Loss Calculator

HDDuctDesigner 9.5 has just been released (Summer 2026). This is a total rewrite of our duct design software tool that completely revamps the user interface, making it more user friendly and, of course, it includes a slew of new features including the following major updates:

  1. Side-by-side equal-friction sizing for Rectangular, Round, and Oval duct shapes from a single airflow input.
  2. An expanded round and rectangular duct fitting pressure-loss library, complete with on-screen reference diagrams that highlight the selected fitting.
  3. Now exports a professionally formatted PDF report with print preview, direct printing, and copy-to-clipboard support.
  4. Totally revamped user interface that accommodates all manner of screen resolutions and scaling.
At its core, HDDuctDesigner allows you to quickly size supply and return ductwork and evaluate fitting pressure losses for a project, without having to flip through paper duct calculators or ASHRAE tables. Enter your airflow, choose a duct material and shape, and HDDuctDesigner instantly computes velocity, friction rate, pressure drop, velocity pressure, and cross-sectional area — for Rectangular, Round, and Oval ducts simultaneously.

HDDuctDesigner also includes a built-in duct fitting pressure-loss calculator based on the ASHRAE "HVAC Simplified" equal-friction/equivalent-length method, a duct wall temperature gain/loss calculator, a duct weight estimator, and a Pitot-tube CFM back-calculation tool for field verification and air balancing.

Both IP and SI units are fully supported, with instant one-click switching between unit systems.


KEY FEATURES OF HDDUCTDESIGNER

  • Equal-friction duct sizing for Rectangular, Round, and Oval duct shapes, computed side by side from one airflow entry
  • Duct material/roughness library with 13 built-in materials (galvanized steel, PVC, aluminum, fiberglass duct board, flexible duct, concrete, and more) plus a user-defined roughness option
  • Standard Air or Actual Air density modeling, with actual air density computed from altitude and a selectable psychrometric state point via a built-in psychrometric engine
  • Round duct fitting library covering elbows, reducers, tees, wyes, boots, saddles, plenum takeoffs, and return fittings
  • Rectangular duct fitting library covering elbows (with and without vanes), tees, transitions, take-offs, and return fittings
  • Dynamic on-screen fitting reference diagrams that highlight the currently selected fitting
  • Duct wall temperature gain/loss calculator based on insulation R-value, surface area, and temperature differential
  • Duct weight estimator by sheet material (galvanized steel, stainless steel, aluminum) and gauge
  • Pitot-tube CFM back-calculation for field verification and air balancing
  • Built-in R-Value reference chart and Pitot tube diagram
  • One-click IP (Imperial) / SI (Metric) unit switching for every input and result field
  • Professional PDF report generation with print preview, direct printing, and copy-to-clipboard export
View more app screenshots here.

  • HDDuctDesigner - Duct Fitting
  • HDDuctDesigner - Duct Sizing Calculation Results
  • HDDuctDesigner - PDF Report
  • HDDuctDesigner - Metric (SI) Units
  • HDDuctDesigner - Duct Material

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