AWSM Tools

Convert ellipsoids


Universal Transverse Mercator (UTM)

UTM is conformal projection uses a 2-dimensional Cartesian coordinate system to give locations on the surface of the Earth. It is a horizontal position representation, i.e. it is used to identify locations on the Earth independently of vertical position, but differs from the traditional method of latitude and longitude in several respects.

The UTM system is not a single map projection. The system instead divides the Earth into sixty zones, each a six-degree band of longitude, and uses a secant transverse Mercator projection in each zone.

Grid zone

The combination of a zone and a latitude band defines a grid zone. The zone is always written first, followed by the latitude band.


The UTM system divides the Earth into 60 zones, each 6° of longitude in width.

Latitude band

Each zone is segmented into 20 latitude bands. Each latitude band is 8° high, and is lettered from "C" to "X", omitting the letters "I" and "O".

Grid zone exceptions

On the southwest coast of Norway, grid zone 32V (9° of longitude in width) is extended further west, and grid zone 31V (3° of longitude in width) is correspondingly shrunk to cover only open water.

In the region around Svalbard, the four grid zones 31X (9° of longitude in width), 33X (12° of longitude in width), 35X (12° of longitude in width), and 37X (9° of longitude in width) are extended to cover what would otherwise have been covered by the seven grid zones 31X to 37X.

All exceptions are considered.

Ellipsoid (datum)

Ellipsoids describe the shape of the earth used to calculate the UTM grid. Available ellipsoids:

  • Airy
  • Australian National
  • Bessel 1841
  • Bessel 1841 Nambia
  • Clarke 1866
  • Clarke 1880
  • Everest 1830 India
  • Everest 1830 Malaysia
  • Everest 1956 India
  • Everest 1964 Malaysia and Singapore
  • Everest 1969 Malaysia
  • Everest Pakistan
  • Fischer 1960 Mercury
  • Fischer 1968
  • GRS 1967
  • GRS 1980
  • Helmert 1906
  • Hough
  • Indonesian 1974
  • International
  • Krassovsky
  • Modified Airy
  • Modified Everest
  • Modified Fischer 1960
  • South American 1969
  • WGS 60
  • WGS 66
  • WGS 72
  • WGS 84


Decimal degrees
Degrees decimal minutes
Global Area Reference System
World Geographic Reference System
Universal Transverse Mercator
United States National Grid
Military Grid Reference System