Question

How do I calculate the distance between two points specified by latitude and longitude?

For clarification, I’d like the distance in kilometers; the points use the WGS84 system and I’d like to understand the relative accuracies of the approaches available.

Answer 1

This link might be helpful to you, as it details the use of the Haversine formula to calculate the distance.

Excerpt:

This script [in Javascript] calculates great-circle distances between the two points – that is, the shortest distance over the earth’s surface – using the ‘Haversine’ formula.

function getDistanceFromLatLonInKm(lat1,lon1,lat2,lon2) {   var R = 6371; // Radius of the earth in km   var dLat = deg2rad(lat2-lat1);  // deg2rad below   var dLon = deg2rad(lon2-lon1);    var a =      Math.sin(dLat/2) * Math.sin(dLat/2) +     Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2)) *      Math.sin(dLon/2) * Math.sin(dLon/2)     ;    var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));    var d = R * c; // Distance in km   return d; }  function deg2rad(deg) {   return deg * (Math.PI/180) }