GIS Projection Finder
Search 30+ coordinate reference systems by EPSG code, name, country, or use case. Get Proj4 strings, WKT definitions, and practical usage notes instantly.
What This Tool Does
A quick-reference database of common coordinate reference systems with everything you need to use them.
27700, a name like "Lambert", a country like "Germany", or a keyword like "equal area". Results update as you type.Frequently Asked Questions
An EPSG code is a unique numeric identifier for a coordinate reference system (CRS), maintained by the EPSG Geodetic Parameter Dataset (now IOGP). For example, EPSG:4326 is WGS 84 geographic, EPSG:3857 is Web Mercator, and EPSG:27700 is the British National Grid. EPSG codes are used in GIS software, spatial databases, and APIs to unambiguously specify how coordinates should be interpreted.
A geographic CRS uses angular units (degrees) and defines positions on a 3D ellipsoid model of the Earth — examples: WGS 84 (EPSG:4326), NAD83 (EPSG:4269). A projected CRS uses linear units (metres or feet) and maps the ellipsoid onto a flat 2D surface — examples: Web Mercator (EPSG:3857), UTM zones, British National Grid. You need a projected CRS for accurate distance and area calculations; geographic CRS coordinates cannot be directly used for those operations.
A Proj4 string is a compact text format used by the PROJ library to define a CRS. It lists projection parameters as key=value pairs prefixed with +. Example: +proj=utm +zone=32 +datum=WGS84 +units=m +no_defs. Proj4 strings are used in Python (pyproj), GDAL/OGR, QGIS, PostGIS, and most open-source GIS tools to specify or reproject coordinate systems.
Use EPSG:4326 (WGS 84) for storing and exchanging geographic data — it is the standard for GPS, GeoJSON, and most APIs. Use EPSG:3857 (Web Mercator) only for rendering web map tiles from Google Maps, OpenStreetMap, or Mapbox basemaps. Never use EPSG:3857 for area or distance calculations — it treats Earth as a sphere and distorts areas severely at high latitudes. If you need to measure distances or areas, reproject to a suitable local projected CRS first.
UTM divides the world into 60 zones of 6° longitude each. Formula: zone = floor((longitude + 180) / 6) + 1. Examples: London (0°) → zone 30 (EPSG:32630), New York (74°W) → zone 18 (EPSG:32618), Tokyo (139°E) → zone 54 (EPSG:32654), Sydney (151°E) → zone 55S (EPSG:32755). Northern hemisphere: EPSG:326XX. Southern hemisphere: EPSG:327XX. Where XX is the two-digit zone number.