# ST_Area function

The ST_Area function takes a geometry and, optionally, a unit as input parameters and returns the area covered by the geometry.

If the geometry is a polygon or multipolygon, then the area covered by the geometry is returned. The area of points, linestrings, multipoints, and multilinestrings is 0 (zero). If the geometry is null or is an empty geometry, null is returned.

## Syntax

## Parameters

- geometry
- A value of type ST_Geometry or one of its subtypes that represents the geometry that determines the area.
- unit
- A VARCHAR(128) value that identifies the units in which the area
is measured. The supported units of measure are listed in the SYSGEO.ST_UNITS_OF_MEASURE
catalog view. If the
*unit*parameter is omitted, the following rules are used to determine the unit in which the area is measured:- If
*geometry*is in a projected or geocentric coordinate system, the linear unit associated with this coordinate system is used. - If
*geometry*is in a geographic coordinate system, the angular unit associated with this coordinate system is used.

**Restrictions on unit conversions:**An error (SQLSTATE 38SU4) is returned if any of the following conditions occur:- The geometry is in an unspecified coordinate system and the
*unit*parameter is specified. - The geometry is in a projected coordinate system and an angular unit is specified.
- The geometry is in a geographic coordinate system, and a linear unit is specified.

- If

## Return type

DOUBLE

## Examples

- Example 1
- The spatial analyst needs a list of the area covered by each sales region. The sales region polygons are stored in the SAMPLE_POLYGONS table. The area is calculated by applying the ST_Area function to the geometry column.
`call st_create_srs ('NEW_YORK1983', 4000, 0, 0, 1, 0, 1, 0, 1, 'NAD_1983_STATEPLANE_NEW_YORK_EAST_FIPS_3101_FEET', '') CREATE TABLE sample_polygons (id INTEGER, geometry ST_POLYGON) INSERT INTO sample_polygons (id, geometry) VALUES (1, ST_Polygon('polygon((0 0, 0 10, 10 10, 10 0, 0 0))', 4000) ), (2, ST_Polygon('polygon((20 0, 30 20, 40 0, 20 0 ))', 4000) ), (3, ST_Polygon('polygon((20 30, 25 35, 30 30, 20 30))', 4000))`

The following SELECT statement retrieves the sales region ID and area:`SELECT id, ST_Area(geometry) AS area FROM sample_polygons`

Results:`ID AREA -------- ------------------------ 1 +1.00000000000000E+002 2 +2.00000000000000E+002 3 +2.50000000000000E+001`

- Example 2
- The following SELECT statement retrieves the sales region ID and area in various units:
`SELECT id, ST_Area(geometry) square_feet, ST_Area(geometry, 'METER') square_meters, ST_Area(geometry, 'STATUTE MILE') square_miles FROM sample_polygons`

Results:`ID SQUARE_FEET SQUARE_METERS SQUARE_MILES -- ---------------------- ---------------------- ---------------------- 1 +1.00000000000000E+002 +9.29034116132749E+000 +3.58702077598428E-006 2 +2.00000000000000E+002 +1.85806823226550E+001 +7.17404155196855E-006 3 +2.50000000000000E+001 +2.32258529033187E+000 +8.96755193996069E-007`

- Example 3
This example finds the area of a polygon defined in State Plane coordinates.

The State Plane spatial reference system with an ID of 3 is created with the following command:`call st_create_srs('Z3101A', 30, 0, 0, 1, 0, 1, 0, 1, 'NAD_1983_STATEPLANE_NEW_YORK_EAST_FIPS_3101_FEET', '')`

The following SQL statements add the polygon, in spatial reference system 3, to the table and determines the area in square feet, square meters, and square miles.`CREATE TABLE Sample_Poly3 (id integer, geometry ST_Polygon); INSERT into Sample_Poly3 VALUES (1, ST_Polygon('polygon((567176.0 1166411.0, 567176.0 1177640.0, 637948.0 1177640.0, 637948.0 1166411.0, 567176.0 1166411.0 ))', 30)); SELECT id, ST_Area(geometry) "Square Feet", ST_Area(geometry, 'METER') "Square Meters", ST_Area(geometry, 'STATUTE MILE') "Square Miles" FROM Sample_Poly3;`

Results:`ID SQUARE FEET SQUARE METERS SQUARE MILES -- ---------------------- ---------------------- ---------------------- 1 +7.94698788000000E+008 +7.38302286101346E+007 +2.85060106320552E+001`