HVAC Duct Sizing
Size ductwork instantly. Compare 4 simultaneous profiles, calculate CFM, velocity, and friction loss with visual scaled diagrams — all based on ASHRAE Fundamentals.
Built for HVAC engineers, mechanical designers, and sheet metal detailers.
Compare 2 rectangular, 1 round, and 1 flat oval profile side by side. See all your options at once.
Enter any two of CFM, velocity (FPM), or friction loss (in. wg/100ft) and the third calculates automatically.
Galvanized steel, stainless steel, aluminum, fiberglass board, and flex duct — each with accurate roughness factors.
See duct cross-sections drawn to scale with live dimension labels. Aspect ratio displayed for manufacturability checks.
Toggle snap-to-standard to lock dimensions to standard manufactured sizes. No guesswork.
Share duct sizing results directly with your team from the app. ASHRAE Equal Friction Loss method documented.
Get Interactive Ductulator plus Pipe Schematic Pro and Point Load Calculator for just $7.99 instead of $10.97.