DXF is originally created in Metric units - Centimetres.
The importing process varies depending on the software you are using.
Importing DXF Files:
AutoCAD:
Start a new project in AutoCAD using a template with Imperial or Metric units, depending on your need.
Go to Files > Import and select the DXF file.
Note: if you simply open a DXF file in AutoCAD, one drawing unit will be equal to one centimetre from the DXF file.
Chief Architect:
Select File > Import > Import Drawing (DXF, DXF) from the menu.
Follow the Import Drawing Assistant dialog that displays.
Under Drawing Unit, when it asks “What unit of measurement was used to create the imported drawing?” select “cm” for centimetres.
Autodesk Revit:
Open Revit project and click Insert.
Choose Link CAD or Import CAD.
Find the DXF file and select centimetre under Import units.