I'm a mac user and I haven't come across any pattern designing software for mac. There is a motif maker for OS X, but that won't give you any calculations.
If you can get your hands on a copy of Ann Budd's The Knitter's Handy Book of Knitting Pattern, it may help you correlate your figures.
Amy sells it in the KH shop here and calls it her most used pattern book for sweaters, hats, mittens, etc. It's very versatile.