CSAT: Frequently Asked Questions

What is the difference between UTM and MGRS coordinates?
 MGRS coordinates are very closely related to UTM coordinates, but there are some differences. Both systems divide the world into 60 zones of longitude the same way. But, to identify the squares which are 100,000 meters on a side, MGRS uses two letters, where UTM uses 1 or 2 digits. MGRS inserts a latitude band letter after the longitude zone number. The latitude bands are 8 degrees tall, with the Equator separating bands M and N. For details and excpetions see: UTM basics

How do latitude and longtitude equate to length ?
 In the simple spherical model the following relationship holds true.
 1 second of Latitude = 30 meters
 1 second of Longitude = (30 m) * Cos(Lat)
 The relationships for the ellipsoid model are more complicated. To see the mathematical relationships for the ellipsoid model click here. Ellipsoid Model.
Point of Contact: Coordinate Systems Analysis Team
phone (314) 6769124, DSN 8469124
coordsys@nga.mil
phone (314) 6769124, DSN 8469124
coordsys@nga.mil
Document last modified April 29, 2013