How to Determine the Grid Coordinates of a Point on a Military Map
Like many other maps, military maps have a grid of horizontal and vertical lines printed on them. These lines break the map into squares, each grid square representing 1 square kilometer on the ground. The coordinates of any point on the map can be expressed in relation to the grid squares. Determining coordinates enables you to locate specific points, find your way with confidence, and accurately describe locations to other people.
Other People Are Reading
Instructions
-
-
1
Read the number of the vertical grid line to the left of the location for which you want to find the grid coordinate. If the location does not lie exactly on the line, estimate the distance between the line and the location by dividing the grid square into tenths.
-
2
Write down the line number and the estimated number of tenths to the next line. For example, if the line to the left is 25 and you estimate the location to be another three tenths of the way between that line and the next, write down the numerals 25 and 3, to read 253.
-
-
3
Read the number of the horizontal line below the location for which you want to establish the grid coordinate. If the location does not lie exactly on the line, estimate the distance between that line and the location by dividing the grid square into tenths.
-
4
Write down the line number and the estimated number of tenths up to the next line. For example, if the line number is 44 and you estimate the location to be up another six tenths of the way between that line and the next, write down the numerals 44 and 6, to read 446
-
5
Combine the two grid coordinates to form the grid reference, writing the vertical coordinate first, followed immediately by the horizontal coordinate. In this example, the grid reference is 253445.
-
1
Tips & Warnings
Use a transparent coordinate scale and protractor marked in millimeters to help estimate tenths across a grid square.
The base of most compasses has a scale marked on it. You can use that to measure tenths across grid squares.
Right and Up are also called Eastings and Northings because they increase in value toward the east and north.
Grid references consist of four, six, eight or 10 digits, depending on the level of accuracy required.
Writing the horizontal coordinates before the vertical ones will produce an entirely different set of coordinates.
Practice finding and reading map coordinates in good weather before you need to depend on your skill.
Always check military maps for dangers and zones you may not enter.
References
- Army Board Study Guide: Determine the Grid Coordinates of a Point on a Military Map
- U.S. National Grid: A Google Maps Demonstration of the Official Map Coordinate System of the United States
- Army Board Study Guide: Locate a Point Using the US Army Military Grid Reference System (MGRS)
- Survival IQ: Locate a Point Using Grid Coordinates
- ABC of Hiking: Compass Navigation & Using a Compass
- The Federal Geographic Data Committee: Reading US National Grid Coordinates
Resources
- Photo Credit David J Spurdens/Digital Vision/Getty Images
