Tap File Dimensions not right

I imported a DXF file (one circle) with a dia. of 13.5625 inches. When I format to a tap file the dia. measures .53 inches. I am using the free version of sheetcam at the moment. Am I doing something wrong or do I have to purchase sheetcam to do circles. The program has about 25 lines.

Your units must be set to millimetres in options/application options/units

Or, when you imported your dxf, it asks metric or inches, you have to select inches