ST_Length¶

Introduction: 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 authalic 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.

Format:

ST_Length (A: Geography)

Return type: Double

Since: v1.9.1

SQL Example

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

Output (in meters):

111195.10117748393

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