What it does
Size
Airflow plus friction rate, velocity or both. Exact round size and the next stock size up, rectangles and flat ovals of equal friction, the velocity band for the duct's job, 14 materials, compressed flex, temperature and elevation.
Fit
Joist and I-joist bays drawn to scale, ceiling spaces or your own opening. When one duct will not fit, it splits the air into two runs.
Design
Design friction rate from the blower's static, coil, filter and longest paths. Whole systems: every section sized, the critical path found, damper settings and the static the blower must deliver.
Field tools
Airflow from a load or tons, airflow per room, air changes, registers, fan laws, pitot traverse, psychrometrics, mixed air, condensation, leakage, sheet metal, offsets and a unit converter.
Shows its work
Every size explains itself: air density, velocity, Reynolds number, Colebrook and Darcy-Weisbach with your numbers. Checked against ASHRAE tables and worked examples.
For the job
Save runs by job, share a one-page duct schedule as PDF or a spreadsheet. US and metric units, light and dark, English, Spanish and French.