The diagram editor needs a larger screen and a mouse or trackpad. Modeling and calculation controls are not available in this mobile view.
Use this page on a desktop or laptop to build a system, review pressure losses, and prepare a calculation report. If you resized an open model, your canvas is still available when you return to a larger window.
A 600 CFM office supply: a fan, 20 ft of 12 in round duct, one smooth 90° elbow, another 10 ft of duct, and a diffuser with an assumed 0.10 in. w.g. drop.
On desktop, choose Load Example to calculate it. This is illustrative geometry, not a verified design or fan selection.
Illustrative inputs. Review geometry and assumptions before design use.
🔊 Hover a fan or diffuser to hear its estimated sound (relative, not calibrated)
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Duct Static Pressure Calculator
DuctStatic is a free online duct static pressure calculator for HVAC engineers and designers. Model a complete duct system with fans, straight duct runs, elbows, tees, transitions, dampers, diffusers, and terminal units, then compute the total pressure loss using the total pressure loss method.
The calculation engine uses Idelchik duct fitting loss coefficients. For each component it calculates friction loss from straight duct runs and dynamic loss from fittings and transitions, correcting for site altitude, air temperature, and air density (ideal gas law). The critical path is the modeled run with the highest total pressure loss. This is modeled system pressure loss, not a complete fan selection: unmodeled equipment losses and fan inlet/outlet conditions require separate review.
Features include velocity and pressure-drop per 100 ft, round and rectangular duct sizing output, an interactive diagram with pressure profile chart, preliminary acoustic/sound estimation, print-to-PDF export, and cloud project save/load. DuctStatic is free to use with no registration required.
Results are for estimation purposes only and must be verified by a qualified engineer before use in design or construction.