easting

Easting is a term used in cartography and geospatial analysis to refer to the x-coordinate in a projected coordinate reference system. It represents the distance eastward from the grid origin along the projection's x-axis, and is usually expressed in linear units such as meters or feet. Coordinates are typically written as (easting, northing), with northing providing the corresponding north–south position.

Easting differs from geographic longitude. Longitude measures angular distance east or west on the ellipsoid, while easting is a linear distance that results from applying a map projection. Because a projection distorts distances, directions, and areas to some degree, easting values are meaningful only within the context of a specific projection and its grid.

Projections often include a false origin to keep coordinates positive. For example, the Universal Transverse Mercator (UTM) system uses a central meridian with an easting of 500,000 meters; points to the east or west have easting values above or below this reference. Typical easting values within a UTM zone stay within a range roughly centered around 500,000 meters, commonly spanning approximately 166,000 to 833,000 meters.

Other grid systems, such as the British National Grid or state plane coordinate systems, define their own origins and units but share the same concept: easting denotes the east–west position on the grid, while northing denotes the south–north position. Easting is fundamental in surveying, mapping, and GIS for locating features, measuring distances, and performing spatial analyses within a projected framework.