WKT (Well-Known Text)
A plain-text format for geometries (e.g., POLYGON, MULTIPOLYGON) widely used in GIS and spatial databases.
Category: Formats · Also known as: Well Known Text, OGC WKT
Definition (expanded)
WKT (Well-Known Text) encodes a single geometry as text, such as POLYGON((...)) or MULTIPOLYGON(((...))). It's common in PostGIS, BigQuery GIS, and desktop GIS workflows. WKT represents one geometry value. Multiple features are typically stored as multiple rows, or wrapped in a GEOMETRYCOLLECTION or a MULTI* geometry.
Examples
Polygon (WKT)
Coordinates shown as lon lat.
WKT
POLYGON((12.0 55.0, 12.2 55.0, 12.2 55.2, 12.0 55.2, 12.0 55.0))
Common mistakes
- Swapping latitude/longitude (WKT is almost always lon lat in EPSG:4326 contexts).
- Forgetting to close rings (first coordinate must equal last).
Related tools
Related terms
EWKT (Extended WKT)A PostGIS-style WKT string that can include SRID, like SRID=4326;POLYGON((...)).GeoJSONA JSON format for geographic features, using objects like Feature, FeatureCollection, and geometry types like Polygon and MultiPolygon.WKB (Well-Known Binary)A compact binary format for geometries, widely used in spatial databases and APIs.EWKB (Extended WKB)A PostGIS extension to WKB that can include SRID and additional flags.PolygonA closed area geometry defined by an exterior ring and optional interior rings (holes).MultiPolygonA geometry containing multiple polygons (parts), each with its own exterior ring and optional holes.GeometryCollectionA single geometry that contains multiple geometries, which can be different types (Polygon, MultiPolygon, etc.).