Calculating Distance between two Latitude and Longitude GeoCoordinates

The GeoCoordinate class (.NET Framework 4 and higher) already has GetDistanceTo method.

var sCoord = new GeoCoordinate(sLatitude, sLongitude);
var eCoord = new GeoCoordinate(eLatitude, eLongitude);

return sCoord.GetDistanceTo(eCoord);

The distance is in meters.

You need to reference System.Device.

GetDistance is the best solution, but in many cases we can't use this Method (e.g. Universal App)

• Pseudocode of the Algorithm to calculate the distance between to coorindates:

  public static double DistanceTo(double lat1, double lon1, double lat2, double lon2, char unit = 'K')
  {
      double rlat1 = Math.PI*lat1/180;
      double rlat2 = Math.PI*lat2/180;
      double theta = lon1 - lon2;
      double rtheta = Math.PI*theta/180;
      double dist =
          Math.Sin(rlat1)*Math.Sin(rlat2) + Math.Cos(rlat1)*
          Math.Cos(rlat2)*Math.Cos(rtheta);
      dist = Math.Acos(dist);
      dist = dist*180/Math.PI;
      dist = dist*60*1.1515;
  
      switch (unit)
      {
          case 'K': //Kilometers -> default
              return dist*1.609344;
          case 'N': //Nautical Miles 
              return dist*0.8684;
          case 'M': //Miles
              return dist;
      }
  
      return dist;
  }
  

• Real World C# Implementation, which makes use of an Extension Methods

  Usage:

  var distance = new Coordinates(48.672309, 15.695585)
                  .DistanceTo(
                      new Coordinates(48.237867, 16.389477),
                      UnitOfLength.Kilometers
                  );
  

  Implementation:

  public class Coordinates
  {
      public double Latitude { get; private set; }
      public double Longitude { get; private set; }
  
      public Coordinates(double latitude, double longitude)
      {
          Latitude = latitude;
          Longitude = longitude;
      }
  }
  public static class CoordinatesDistanceExtensions
  {
      public static double DistanceTo(this Coordinates baseCoordinates, Coordinates targetCoordinates)
      {
          return DistanceTo(baseCoordinates, targetCoordinates, UnitOfLength.Kilometers);
      }
  
      public static double DistanceTo(this Coordinates baseCoordinates, Coordinates targetCoordinates, UnitOfLength unitOfLength)
      {
          var baseRad = Math.PI * baseCoordinates.Latitude / 180;
          var targetRad = Math.PI * targetCoordinates.Latitude/ 180;
          var theta = baseCoordinates.Longitude - targetCoordinates.Longitude;
          var thetaRad = Math.PI * theta / 180;
  
          double dist =
              Math.Sin(baseRad) * Math.Sin(targetRad) + Math.Cos(baseRad) *
              Math.Cos(targetRad) * Math.Cos(thetaRad);
          dist = Math.Acos(dist);
  
          dist = dist * 180 / Math.PI;
          dist = dist * 60 * 1.1515;
  
          return unitOfLength.ConvertFromMiles(dist);
      }
  }
  
  public class UnitOfLength
  {
      public static UnitOfLength Kilometers = new UnitOfLength(1.609344);
      public static UnitOfLength NauticalMiles = new UnitOfLength(0.8684);
      public static UnitOfLength Miles = new UnitOfLength(1);
  
      private readonly double _fromMilesFactor;
  
      private UnitOfLength(double fromMilesFactor)
      {
          _fromMilesFactor = fromMilesFactor;
      }
  
      public double ConvertFromMiles(double input)
      {
          return input*_fromMilesFactor;
      }
  }