UTM

The Universal Transverse Mercator (UTM) is a geographic coordinate system that maps the Earth’s surface onto a two-dimensional plane using the Transverse Mercator projection. It provides metric coordinates in meters, which facilitates accurate distance, area, and navigation calculations for many mapping and GIS applications.

The world is divided into 60 north–south zones, each 6 degrees of longitude wide. Zones are numbered 1 through 60 from west to east. Each zone has a central meridian, and to ensure all coordinates are positive, a false easting of 500,000 meters is added to the easting value. In the northern hemisphere, northing is measured from the equator; in the southern hemisphere, a false northing of 10,000,000 meters is added to avoid negative values.

Within a zone, the projection uses a standard scale factor of 0.9996 at the central meridian. Coordinates are expressed as easting and northing in meters, and are typically defined relative to a geodetic datum such as WGS84, though regional datums have been used in the past (e.g., NAD27).

UTM offers relatively low distortion within a single zone and provides convenient metric units for location measurements, making it popular in mapping, surveying, and geographic information systems. However, its main limitation is that distortion increases near zone boundaries, and large areas that span multiple zones require coordinates from multiple zones or a different projection system. For widespread or global mapping, alternative projections or a chain of UTM zones is often used.