Military Grid Reference System: Difference between revisions

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{{Short description|NATO global coordinate reference system}}

{{Geodesy}}

The '''Military Grid Reference System''' ('''MGRS''') is the geocoordinate standard used by [[NATO]] militaries for geo-referencing, position reporting, and situational awareness during land operations.<ref>{{cite web |url=https://www.jcs.mil/Portals/36/Documents/Library/Instructions/CJCSI%203900.01E.pdf |title=CJCSI 3900.01E Position (POS), Navigation, and Timing (PNT) and Global Positioning System (GPS) Requirements |publisher=Chairman of the Joint Chiefs of Staff |date=1410 DecemberFebruary 20182023 |access-date=27 June 2025 |page=A-2 |quote=The Military Grid Reference System (MGRS) is the standard for military land operations for geo-referencing and position reporting.}}</ref> An MGRS coordinate does not represent a single point, but rather defines a square grid area on the Earth's surface. The ___location of a specific point is therefore referenced by the MGRS coordinate of the area that contains it. The MGRS is derived from the [[Universal Transverse Mercator coordinate system|Universal Transverse Mercator]] (UTM) and [[Universal Polar Stereographic coordinate system|Universal Polar Stereographic]] (UPS) grid systems and is used as a [[geocode]] for the entire Earth.

An example of an ''MGRS coordinate'', or ''grid reference'', is [{{Coor URL}}21_24_35.43062452380_N_157_54_57.89102787040_W_&language=en <code>4Q FJ 1234 6789</code>], which consists of three parts:

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|+ MGRS precision levels

! MGRS Coordinate

! Precision (side length)

|-

| <code>4Q FJ</code>

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==Grid zone designation==

[[File:Universal_Transverse_Mercator_zones.svg|thumb|300px|UTM zones on an equirectangular world map with irregular zones in red and New York City's zone highlighted]]

The first part of an MGRS coordinate is the ''grid-zone designation''. The 6° wide UTM zones, numbered 1–60, are intersected by latitude bands that are normally 8° high, lettered C–X (omitting I and O). The northmost latitude band, X, is 12° high. The intersection of a UTM zone and a latitude band is (normally) a 6° × 8° polygon called a ''grid zone'', whose ''designation'' in MGRS is formed by the zone number (one or two digits – the number for zones 1 to 9 is just a single digit, according to the example in DMA TM 8358.1, Section 3-2,<ref name="DMA8358_1_Chapter3">[http://earth-info.nga.mil/GandG/publications/tm8358.1/tr83581b.html#ZZ26 DMA Technical Manual 8358.1, Chapter 3.] Datums, Ellipsoids, Grids, and Grid Reference Systems</ref> Figure 7), followed by the latitude band letter (uppercase). This same notation is used in both UTM and MGRS, i.e. the UTM grid reference system; the article on [[Universal Transverse Mercator]] shows many maps of these grid zones, including the irregularities for Svalbard and southwest Norway.

As Figure 1 illustrates, Honolulu is in grid zone 4Q.