ArcGIS Pro 2.6 API Reference Guide
GeodesicArea Method (GeometryEngine)
Example 

ArcGIS.Core.Geometry Namespace > GeometryEngine Class : GeodesicArea Method
The intput geometry.
Gets the geodesic area of a polygon.
Syntax
public double GeodesicArea( 
   Geometry geometry
)
Public Function GeodesicArea( _
   ByVal geometry As Geometry _
) As Double

Parameters

geometry
The intput geometry.

Return Value

The calculated geodesic area. The area returned is in square meters.
Exceptions
ExceptionDescription
Geometry is null or empty.
The method is not implemented for GeometryBag or Multipatch.
Geometry is of the wrong type (e.g. a polyline).
Spatial reference of geometryis an image coordinate system.
Example
var polygon = PolygonBuilder.CreatePolygon(new[]
{
  MapPointBuilder.CreateMapPoint(-10018754.1713946, 10018754.1713946),
  MapPointBuilder.CreateMapPoint(10018754.1713946, 10018754.1713946),
  MapPointBuilder.CreateMapPoint(10018754.1713946, -10018754.1713946),
  MapPointBuilder.CreateMapPoint(-10018754.1713946, -10018754.1713946)
}, SpatialReferences.WebMercator);
var area = GeometryEngine.Instance.GeodesicArea(polygon);

// area is close to 255032810857732.31
Requirements

Target Platforms: Windows 10, Windows 8.1, Windows 7

See Also

Reference

GeometryEngine Class
GeometryEngine Members