> ## Documentation Index
> Fetch the complete documentation index at: https://docs.wherobots.com/llms.txt
> Use this file to discover all available pages before exploring further.

# ST_Length

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`.

<img src="https://mintcdn.com/wherobots/rE_Ak061k3dknbDZ/images/sql-functions/ST_Length_geography/ST_Length_geography.svg?fit=max&auto=format&n=rE_Ak061k3dknbDZ&q=85&s=92ef0f1ee9693db216a0d135c3669722" alt="ST_Length on a Geography on the sphere" width="540" height="320" data-path="images/sql-functions/ST_Length_geography/ST_Length_geography.svg" />

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.

## Signatures

```sql theme={"system"}
ST_Length (A: Geography)
```

## Parameters

<ParamField body="A" type="Geography" required>
  The geography whose spherical length is returned.
</ParamField>

## Return type

<ResponseField type="Double">
  The spherical length in meters (`0.0` for non-linear input).
</ResponseField>

## Example

```sql theme={"system"}
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`.