
Setting your Inkscape Preferences to a geometric bounding box will ensure that both bounding box dimensions on tool and in Inkscape match up with one another. Origin calculates the bounding box based upon the middle of the stroke. Inkscape defaults to a visual bounding box, which includes stroke width in its calculation of the bounding box's dimensions. Go to Edit > Preferences > Tools and select 'Geometric Bounding Box'. Go to Edit > Preferences > Input/Output > SVG Output and match your settings to those found below. The Inkscape SVG file type will include extraneous data that will not be used by Origin. Save your file as a 'Plain SVG' rather than the 'Inkscape SVG' that Inkscape defaults to.

*Note that the scale value (underlined above) will change based upon your selected units (Inkscape will default to 96 points per inch and 3.77953 points per millimeter) Make sure that your display units and document units match.

Go to File > Document Properties to select your default units.
