The ASHRAE Duct Fitting Database with Excel Link is the definition of a "force multiplier." It does not replace the engineer's judgment—you still have to select the right fitting type—but it removes the arithmetic drudgery.
The is the industry-standard reference for designing and analyzing ductwork systems. It provides the loss coefficients ($C$-values) required to calculate pressure losses for various duct fittings (elbows, transitions, take-offs, etc.). ashrae duct fitting database excel link
But real fittings require two-dimensional interpolation (e.g., for W/H ratios not in the table). A basic VLOOKUP is insufficient. The ASHRAE Duct Fitting Database with Excel Link
If you need to bring that data into a spreadsheet for custom calculations or system sizing, here are the three working methods: But real fittings require two-dimensional interpolation (e
The database allows engineers to input specific dimensions and flow rates to receive an accurate dynamic loss coefficient ( Cocap C sub o
The full database is copyrighted by ASHRAE. You will not find a legitimate, permanent "free Excel download link" on a public website. However, ASHRAE provides licensed access to the data, and several legitimate pathways allow you to bring it into Excel.