First, convert your locations and zip codes to latitude and longitude. Then use something like this: http://jan.ucc.nau.edu/~cvm/latlon_formula.html http://jan.

First, convert your locations and zip codes to latitude and longitude. Then use something like this: http://jan.ucc.nau.edu/~cvm/latlon_formula.html http://jan.ucc.nau.edu/~cvm/latlon_formula.html