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Reference.org
Military Grid Reference System
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<p>The Military Grid Reference System (MGRS) is the geocoordinate standard used by <a href="/facts/NATO/dCeTddMY">NATO</a> militaries for locating areas on Earth. The MGRS is derived from the <a href="/facts/Universal_Transverse_Mercator_coordinate_system/uXdWEVV3">Universal Transverse Mercator (UTM)</a> grid system and the <a href="/facts/Universal_polar_stereographic_coordinate_system/W0rq6gyj">Universal Polar Stereographic (UPS)</a> grid system, but uses a different labeling convention. The MGRS is used as <a href="/facts/Geocode/RxLUxJ6Y">geocode</a> for the entire Earth. </p><p>An example of an <i>MGRS coordinate</i>, or <i>grid reference</i>, is <a href="https://geohack.toolforge.org/geohack.php?pagename=Military_Grid_Reference_System¶ms=21_24_35.43062452380_N_157_54_57.89102787040_W_&language=en">4Q FJ 1234 6789</a>, which consists of three parts: </p> <ul><li>4Q (grid zone designator, GZD)</li> <li>FJ (the 100,000-meter square identifier)</li> <li>1234 6789 (numerical location; <a href="/facts/Easting_and_northing/YyhuUx2f">easting</a> is 1234 and <a href="/facts/Easting_and_northing/YyhuUx2f">northing</a> is 6789, in this case specifying a location with 10 m resolution)</li></ul> <p>For machine-readability and database storage, all spaces may be removed. </p><p>An MGRS grid reference represents a square area on the Earth's surface, rather than a single point. A <i>grid square</i> references a square on the Earth with a side length of 10 km, 1 km, 100 m, 10 m or 1 m, depending on the precision of the coordinates provided. (In some cases, squares adjacent to a Grid Zone Junction (GZJ) are clipped, so "polygon" is a better descriptor of these areas.) </p> MGRS precision levels<table><tbody><tr><th>MGRS Coordinate</th><th>Precision</th></tr><tr><td>4Q FJ</td><td>100,000-meter square</td></tr><tr><td>4Q FJ 1 6</td><td>10,000-meter square</td></tr><tr><td>4Q FJ 12 67</td><td>1,000-meter square</td></tr><tr><td>4Q FJ 123 678</td><td>100-meter square</td></tr><tr><td>4Q FJ 1234 6789</td><td>10-meter square</td></tr><tr><td>4Q FJ 12345 67890</td><td>1-meter square</td></tr></tbody></table> <p>The number of digits in the numerical location must be even: 0, 2, 4, 6, 8 or 10, depending on the desired precision. When changing precision levels, it is important to <a href="/facts/Truncate/8mEHh0qp">truncate</a> rather than <a href="/facts/Rounding/rCLYXN00">round</a> the easting and northing values to ensure the more precise polygon will remain within the boundaries of the less precise polygon. </p><p>Related to this is the primacy of the southwest corner of the polygon being the labeling point for an entire polygon. In instances where the polygon is not a square and has been clipped by a grid zone junction, the polygon keeps the label of the southwest corner as if it had not been clipped. </p>