There are some excel sheets out there that will do it as well, or make your own, it's not that hard. As long as you have one of the many programs that will read excel under OSX, you'll be fine.

I've been using the electrician.com for so long, I don't even know where my excel sheet is. Another good one they have for raceway sizing is at: http://www.electrician2.com/calculators/rf_calculator.html