Thanks Michael - but I can't seem to get it to work :(

My process for testing was as follows:

- Export a 26x26 mm box to .ai without the fit to page option selected

- Import into Expression 3

- Export as Illustrator 9.0 format

- Import into Inkscape

and it's 70.866 units squared lol

-EDIT-

LOL I just tried the same thing again, creating a new document with another 26mm box, and this time it randomly came out to be 92.125 units squared.

Seems to be completely random :D