By default, all software supports multiple file extensions. AutoCAD Civil 3D supports at least 1 different file extensions. The basic files that AutoCAD Civil 3D supports are .ATC. However, not all of the extensions listed on the list are always used to save the effects of work in AutoCAD Civil 3D. Very often, files with such extensions are used as source data files used by AutoCAD Civil 3D.
AutoCAD Civil 3D can be used to convert file formats between the file extensions listed below. You can open a file with one of the file extensions below via AutoCAD Civil 3D and try to save it in another file format, also supported by AutoCAD Civil 3D.