We have found one software suitable in our database for this conversion.
Both .tif to .ecw files can be typically encountered as graphics files, so a conversion between is highly possible. You will just need to find a graphics editor or converter that supports both TIF (Aldus Tagged Image) and ECW (Enhanced Compressed Wavelet) formats.
Updated: July 20, 2016
A free (for non-commercial purposes) powerful cross-platform media browser, viewer and converter. Compatible with more than 500 formats and also supports export to 70 different file formats. It works on Windows, Linux and macOS (OS X).