Mercator Projection

Overview The Mercator projection, developed by Gerardus Mercator in 1569, is a cylindrical conformal projectionConformal ProjectionA conformal (orthomorphic) projection preserves local angles and shapes on a map, ensuring that the scale at any poin... that maps the Earth onto a cylinder tangent to the equator. Its defining characteristic is that all rhumb lines (lines of constant compass bearing) appear as straight lines, making it invaluable for navigation. The projection preserves local angles and shapes but introduces severe area distortion at high latitudes, progressively stretching features toward the poles.

The Web Mercator projection (EPSG:3857), a simplified variant of the Mercator projection, has become the de facto standard for web mapping platforms including Google Maps, OpenStreetMapOpenStreetMapOpenStreetMap (OSM) is a collaborative, open-source mapping project that creates a free, editable map of the world. B..., Bing Maps, and MapboxMapboxMapbox is a robust platform that equips developers with tools to create highly customizable, interactive maps for web.... Web Mercator treats the Earth as a perfect sphere rather than an ellipsoid, enabling simpler mathematics and efficient square tile generation. It clips the world at approximately 85.06° latitude to produce a square map that divides evenly into tiles. Despite its distortion issues, Web Mercator's computational simplicity and seamless tiling have made it ubiquitous.

The Mercator projection preserves angles perfectly (conformality) but distorts areas increasingly with distance from the equator. Greenland appears roughly the same size as Africa, though Africa is actually 14 times larger. Antarctica appears as an infinitely wide strip. This distortion has been criticized for creating misleading perceptions of relative country sizes. The projection cannot represent the poles at all, as they would project to infinity.

Growing awareness of Mercator's area distortion has led to increased adoption of alternative projections for thematic and reference mapping. Equal-area projections like Mollweide and Equal Earth are recommended for displaying statistical data. The AuthaGraph projection attempts to minimize all distortions simultaneously. Despite criticisms, Mercator and Web Mercator remain entrenched in navigation and web mapping due to their practical advantages.