DuctWheel - HVAC Duct Sizer

DuctWheel sizes HVAC ductwork the way a mechanical designer would — by solving the actual duct friction physics, not by eyeballing a chart. Enter your airflow (CFM) and a target friction rate, and DuctWheel solves for the round duct diameter using the Darcy-Weisbach equation with a Swamee-Jain friction-factor approximation (the same physics behind the SMACNA/ASHRAE duct friction charts). Need a rectangular duct instead? Convert between round and rectangular sizes using the standard ASHRAE equal-friction equivalent-diameter formula, in either direction. Why DuctWheel: - Real duct physics (Darcy-Weisbach + Swamee-Jain), not a static lookup chart - Round-to-rectangular and rectangular-to-round conversion - Galvanized and flex duct roughness presets, or enter your own - Velocity flagged automatically when it's high enough to cause noise - Save calculations to compare runs and jobs - Works completely offline - no account, no ads Reference tool note: this app is a design aid using standard published duct-friction methodology. Always check results against your project specs, local code, or a licensed mechanical engineer for anything code-critical. One-time purchase, no subscription. No data collected.