The path data stored in an SVG file is in "user units". If you want to know what they are in real-world units you should look at the width and height of the svg, as well as the viewBox. If you divide the width and height of the SVG by the width and height of the viewBox you'll get the size of user units. Note that the viewBox attribute acts as a transform, so if you use real-world units within an svg element with a viewBox they'll get the same transformation as the used user units (so if the viewBox attribute would imply a two-fold increase in size for user units the same would happen for all the real-world units inside the svg element).
The relevant chapter in the SVG specification: http://www.w3.org/TR/SVG11/coords.html
Aaron and Sarah Spike wrote:
The other day I was trying to draw a path to scale in inkscape 0.39 (Debian unstable) so that I could borrow the path data, put it into a pdf and print a path to scale spanning multple pages. I noticed that I don't quite understand units in inkscape and I was hoping someone could help me understand.
On the page tab of the document preferences dialog Inkscape appears to use 72 points to one inch. The units in the path data seem to be 90 units to one inch. What units are these? Is there a way to make Inkscape store the path data units as inches or centimeters?
If I change the grid units to inches in a new document, the ruler inches change to inches. When I open the document again for editing the ruler units switch back to the default mm and the grid units stay inches. Is there an independant way to control the ruler units or a way to sync them with the grid?
Is there a way to change the cursor position units? They default to points but change to ruler units while transformig objects.
Thank you, Aaron Spike