This is not a "plug-and-play" black box software like some dedicated ductulators (e.g., Elite CHVAC). It requires a solid understanding of Excel. You are essentially building your own calculator using their engine. If you aren't comfortable with Excel formulas or VBA, the learning curve is steep.
: Includes 200+ round, rectangular, and flat oval fittings with pictorial outlines to help with visual identification. Calculations
If you are still calculating duct losses by hand or using a plastic slide rule, you are working too slowly. The Excel link allows you to build robust, auditable, and repeatable calculation sheets that can be saved for future projects.