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| |
| # ST_Area |
| |
| Introduction: Returns the spherical area of a geography in square meters, calculated on the sphere. The Earth is modeled as a sphere of radius `R = 6 371 008 m` (the mean Earth radius); the result is the area of the polygon's interior on that sphere. Returns `0.0` for non-areal geographies (points, linestrings) and for `NULL`. |
| |
| Multi-polygons sum the children's areas; geography collections recurse into their members. |
| |
|  |
| |
| Each Geography polygon shell is normalized to an area of at most one hemisphere. A shell intended to represent more than half the sphere is therefore interpreted as its complement; reversing the ring's coordinate sequence does not select the larger region. The returned area is bounded by half the surface of the Earth (~2.55 × 10¹⁴ m²). |
| |
| If you specifically want the WGS84 ellipsoidal value (which is ~0.5 % lower for typical shapes), convert via `ST_GeogToGeometry` first and use the geometry overload: |
| |
| ```sql |
| SELECT ST_Area(ST_GeogToGeometry(geog), true) FROM …; |
| ``` |
| |
| Format: |
| |
| `ST_Area (A: Geography)` |
| |
| Return type: `Double` |
| |
| Since: `v1.9.1` |
| |
| SQL Example |
| |
| ```sql |
| SELECT ST_Area(ST_GeogFromWKT('POLYGON ((0 0, 1 0, 1 1, 0 1, 0 0))')); |
| ``` |
| |
| Output (in m²): |
| |
| ``` |
| 1.2364028804392242E10 |
| ``` |
| |
| That is approximately 12,364 km² — the spherical area of a 1°×1° box near the equator. |
