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Returns the spherical length of a geography in meters, calculated on the sphere. The Earth is modeled as a sphere of radius R = 6 371 008 m (the mean Earth radius). Each edge between successive vertices is interpreted as a great-circle arc; the per-edge arc-angles are summed and scaled by R. Multi-linestrings sum the children’s lengths; geography collections recurse and add up the lengths of their linear members. Returns 0.0 for non-linear geographies (points, polygons) and for NULL. ST_Length on a Geography on the sphere If you specifically want the WGS84 ellipsoidal length (which differs from the spherical value by up to ~0.5 % depending on latitude), convert via ST_GeogToGeometry first and call the Geometry-typed ST_Length(..., useSpheroid => true) overload instead.

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Signatures

ST_Length (A: Geography)

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Parameters

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A
Geography
required
The geography whose spherical length is returned.

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Return type

The spherical length in meters (0.0 for non-linear input).

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Example

SELECT ST_Length(ST_GeogFromWKT('LINESTRING (0 0, 1 0)'));

111195.10117748393
The result is approximately 111.2 km — one degree of arc on a sphere of radius R = 6 371 008 m.