Try Converber from http://www.xyntec.com/converber.htm
Also, if you already own a spreadsheet program, you can find the
formulas to calculate square feet and perimeters for free on the Net.
Okay, the spredsheet isn't freeware (unless it's Open Office, but the
forumlas are readily available on websites free of charge---I'm trying
to be helpful---gimme a break here. ;)