How is mileage calculated between two points?
Mileage is computed using the haversine formula and the US Census Bureau’s TIGER data. First, air miles are derived using the latitude and longitude (or weighted center) of each zip code. Next, a 1.4 conversion factor is applied to compensate for the route the driver will have to travel in order to get from the origin to destination, considering a straight path from point A to point B is never likely.