I don't know how I missed this before and I'm sure many of you smart people already know about it. I just found a marvelous, free, online calculator at this link:
http://www.quiltersparadiseesc.com/Calculators.php
In a matter of minutes I had all the calculations I needed for amount of fabric for the top, the amounts for two borders and the amount of fabric and how many strips to cut for the binding(I had a choice of widths of binding also).
Wonderful! I hope you find it helpful too.