1function getDistanceFromLatLonInKm(lat1,lon1,lat2,lon2) {
2  var R = 6371; // Radius of the earth in km
3  var dLat = deg2rad(lat2-lat1);  // deg2rad below
4  var dLon = deg2rad(lon2-lon1); 
5  var a = 
6    Math.sin(dLat/2) * Math.sin(dLat/2) +
7    Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2)) * 
8    Math.sin(dLon/2) * Math.sin(dLon/2)
9    ; 
10  var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a)); 
11  var d = R * c; // Distance in km
12  return d;
13}
14function deg2rad(deg) {
15  return deg * (Math.PI/180)
16}

1  static double coordinateDistance(
2      double lat1, double lng1, double lat2, double lng2) {
3    const p = 0.017453292519943295;
4    const c = cos;
5    final a = 0.5 -
6        c((lat2 - lat1) * p) / 2 +
7        c(lat1 * p) * c(lat2 * p) * (1 - c((lng2 - lng1) * p)) / 2;
8    return 12742 * asin(sqrt(a));
9  }
10
11  // calculate distance from polyline-coordinates (list of locations)
12  static double calculateDistance(
13      {@required List<Location> polylineCoordinates}) {
14    double _totalDistance = 0.0;
15
16    for (int i = 0; i < polylineCoordinates.length - 1; i++) {
17      _totalDistance += coordinateDistance(
18        polylineCoordinates[i].lat,
19        polylineCoordinates[i].lng,
20        polylineCoordinates[i + 1].lat,
21        polylineCoordinates[i + 1].lng,
22      );
23    }
24
25    // distance in KM
26    return _totalDistance;
27  }