ST_Area

Calculates the area of a spatial object.

The units are:

• GEOMETRY objects: spatial reference system identifier (SRID) units

• GEOGRAPHY objects: square meters

Behavior type

Immutable

Syntax

ST_Area( g )

Arguments

g

Spatial object for which you want to calculate the area, type GEOMETRY or GEOGRAPHY

Returns

FLOAT

Supported data types

Data Type	GEOMETRY	GEOGRAPHY (Perfect Sphere)
Point	Yes	Yes
Multipoint	Yes	Yes
Linestring	Yes	Yes
Multilinestring	Yes	Yes
Polygon	Yes	Yes
Multipolygon	Yes	Yes
GeometryCollection	Yes	No

Examples

The following examples show how to use ST_Area.

Calculate the area of a polygon:

=> SELECT ST_Area(ST_GeomFromText('POLYGON((0 0,1 0,1 1,0 1,0 0))'));
 ST_Area
---------
       1
(1 row)

Calculate the area of a multipolygon:

=> SELECT ST_Area(ST_GeomFromText('MultiPolygon(((0 0,1 0,1 1,0 1,0 0)),
   ((2 2,2 3,4 6,3 3,2 2)))'));
 ST_Area
---------
     3
(1 row)

Suppose the polygon has a hole, as in the following figure.

Calculate the area, excluding the area of the hole:

=> SELECT ST_Area(ST_GeomFromText('POLYGON((2 2,5 5,8 2,2 2),
   (4 3,5 4,6 3,4 3))'));
 ST_Area
---------
       8
(1 row)

Calculate the area of a geometry collection:

=> SELECT ST_Area(ST_GeomFromText('GEOMETRYCOLLECTION(POLYGON((20.5 20.45,
   20.51 20.52,20.69 20.32,20.5 20.45)),POLYGON((10 20,30 40,25 50,10 20)))'));
 ST_Area
----------
 150.0073
(1 row)

Calculate the area of a geography object:

=> SELECT ST_Area(ST_GeographyFromText('POLYGON((20.5 20.45,20.51 20.52,
   20.69 20.32,20.5 20.45))'));
     ST_Area
------------------
 84627437.116037
(1 row)