ST_Area

For an input geometry, ST_Area returns the Cartesian area of the 2D projection. The area units are the same as the units in which the coordinates of the input geometry are expressed. For points, linestrings, multipoints, and multilinestrings, the function returns 0. For geometry collections, it returns the sum of the areas of the geometries in the collection.

For an input geography, ST_Area returns the geodesic area of the 2D projection of an input areal geography computed on the spheroid determined by the SRID. The unit of length is in square meters. The function returns zero (0) for points, multipoints, and linear geographies. When the input is a geometry collection, the function returns the sum of the areas of the areal geographies in the collection.

Syntax

ST_Area(geo)

Arguments

geo

A value of data type GEOMETRY or GEOGRAPHY, or an expression that evaluates to a GEOMETRY or GEOGRAPHY type.

Return type

DOUBLE PRECISION

If geo is null, then null is returned.

Examples

The following SQL returns the Cartesian area of a multipolygon.

SELECT ST_Area(ST_GeomFromText('MULTIPOLYGON(((0 0,10 0,0 10,0 0)),((10 0,20 0,20 10,10 0)))'));

 st_area
---------
     100

The following SQL returns the area of a polygon in a geography.

SELECT ST_Area(ST_GeogFromText('polygon((34 35, 28 30, 25 34, 34 35))'));

     st_area
------------------
 201824655743.383

The following SQL returns zero for a linear geography.

SELECT ST_Area(ST_GeogFromText('multipoint(0 0, 1 1, -21.32 121.2)'));

 st_area
---------
       0