EPSG:3857 — WGS 84 / Pseudo-Mercator
Web Mercator — the spherical projection of WGS 84 used by Google Maps, OpenStreetMap, Bing Maps and virtually every web tile service.
PROJ definition
+proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defs +type=crs
Geographic bounds
W -180° S -85.06° E 180° N 85.06°
Convert coordinates with EPSG:3857
About EPSG:3857
EPSG:3857 (also known as WGS 84 / Pseudo-Mercator, Web Mercator, Spherical Mercator, or by deprecated codes EPSG:900913 and EPSG:3785) projects WGS 84 onto a sphere using the Mercator formula, then onto a square plane between roughly ±85.0511° latitude. Coordinates are linear metres, with the origin at the equator and prime meridian.
Although it shares the WGS 84 datum, the calculation deliberately treats the Earth as a sphere — giving conformal tiles whose pixels are square at every zoom level. This made it the de-facto standard for slippy-tile web maps after Google adopted it in 2005. The trade-off is huge area distortion at high latitudes (Greenland appears the size of Africa) and the fact that linear measurements between projected metres are not true ground distances.
Use EPSG:3857 when you display data on a web map, build raster tiles, or need a coordinate system that aligns with Google/Bing/OSM imagery. Avoid it for area calculations, geodesic distance, or anything outside ±85° latitude.
Common use cases
- Tile servers (XYZ, TMS, vector tiles)
- Aligning data with Google Maps / OSM basemaps
- Web GIS rendering with Leaflet, OpenLayers, MapLibre
- Quick visualisation when accuracy of distance/area is not required
Example coordinates
| Place | X / Lon | Y / Lat |
|---|---|---|
| Eiffel Tower, Paris | 255470 | 6250983 |
| Sydney Opera House | 16832023 | -4009379 |
Common transformations from EPSG:3857
- EPSG:3857 → EPSG:4326WGS 84 / Pseudo-Mercator → WGS 84
- EPSG:3857 → EPSG:3395WGS 84 / Pseudo-Mercator → WGS 84 / World Mercator
- EPSG:3857 → EPSG:4978WGS 84 / Pseudo-Mercator → WGS 84
- EPSG:3857 → EPSG:7789WGS 84 / Pseudo-Mercator → ITRF2014
- EPSG:3857 → EPSG:4267WGS 84 / Pseudo-Mercator → NAD27
- EPSG:3857 → EPSG:4269WGS 84 / Pseudo-Mercator → NAD83
- EPSG:3857 → EPSG:6318WGS 84 / Pseudo-Mercator → NAD83(2011)
- EPSG:3857 → EPSG:4322WGS 84 / Pseudo-Mercator → WGS 72
- EPSG:3857 → EPSG:26910WGS 84 / Pseudo-Mercator → NAD83 / UTM zone 10N
- EPSG:3857 → EPSG:26911WGS 84 / Pseudo-Mercator → NAD83 / UTM zone 11N
- EPSG:3857 → EPSG:26912WGS 84 / Pseudo-Mercator → NAD83 / UTM zone 12N
- EPSG:3857 → EPSG:26913WGS 84 / Pseudo-Mercator → NAD83 / UTM zone 13N
Frequently asked questions
- Is EPSG:3857 the same as Google Mercator?
- Yes. EPSG:3857 superseded the unofficial EPSG:900913 ('Google' upside down) and is the canonical code for the projection used by Google Maps, Bing Maps and OpenStreetMap.
- Why doesn't Web Mercator work above 85° latitude?
- Mercator scaling approaches infinity at the poles. Web Mercator clips to ±85.05112878° so that the world fits in a square tile pyramid.
- Can I measure distances in EPSG:3857?
- Not reliably. Linear metres in Web Mercator are only accurate near the equator. For distance, use a local equal-distance projection or compute on the WGS 84 ellipsoid.
- What is the proj4 string for EPSG:3857?
- The proj4 definition for EPSG:3857 is: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defs +type=crs
- Where is EPSG:3857 used?
- EPSG:3857 (WGS 84 / Pseudo-Mercator) is defined for the area: World - 85°S to 85°N.