But real fittings require two-dimensional interpolation (e.g., for W/H ratios not in the table). A basic VLOOKUP is insufficient.
Purchase the ASHRAE Handbook on CD/DVD or Online Access (cost approx. $200–$300). The digital version often includes CSV or tabulated data for many fittings. ashrae duct fitting database excel link
Go to ashrae.org → search "Duct Fitting Database" → Purchase the current version (approx. $250 for non-members). That is the only reliable, accurate, and legal Excel link you will ever need. Author’s Note: Always respect intellectual property. The ASHRAE Duct Fitting Database is the result of decades of costly research. Using a legitimate copy ensures you have the correct coefficients and supports ongoing industry research. But real fittings require two-dimensional interpolation (e