Getting DXF/DWG Imports to the correct Scale

Firstly, never import a dxf file into an existing drawing...

Then, when you import a dxf file and you can’t get the scale right, find an object that you know the size of, something with a dimension on it.

Measure that object after importing.

Select All

From the Menu Bar choose Modify > Scale Objects...

Rescale the drawing to suit using the Scale Objects command.

Select the options:

Scale Text

Entire Drawing

Enter the scale ratio as A/B where:

A= the original size of the object 

B= the size of the object in the imported file

Click on the OK button and the draw will rescale everything.