No legal free link exists. ASHRAE copyrights this data. Check if your employer or university has a license. Never use random Excel files from file-sharing sites—they often contain outdated (pre-1990s) coefficients.
The official ASHRAE database contains over 2,000 fittings. Free versions typically have less than 200. For commercial projects requiring SMACNA compliance, pay for the real database. ashrae duct fitting database excel link
While the official software isn't a native Excel file, most HVAC pros use the DFDB to pull accurate No legal free link exists
This method gives you a live link to the official database—no manual copying. ashrae duct fitting database excel link
: For large projects, the database is often linked directly to design programs like Bentley OpenBuildings