Read UTM Coordinates
The UTM (Universal Transverse Mercator) system is a system of coordinates that describes position on a map. GPS receivers can display locations in UTM coordinates. Most maps, especially those for hikers, display UTM coordinates. They are widely used by Search and Rescue operators and are even becoming more common in guidebooks. This article will show you how to read UTM coordinates.
Steps
- Determine which zone you are in.
- The world is divided into 60 UTM zones.
- Determine which datum to use.
- When you are using UTM coordinates, you need to make sure that you are using a common UTM datum. For instance, you should check to make sure or your GPS is set to the same datum as your map or guidebooks or you should make sure that a search party knows what datum you are using for your coordinates.
- The reference datums that are most commonly used in North America are NAD 27 CONUS and WGS 84.
- Here is how reference datums work. The reference datum is the one place on map from which you measure to all of the other places. Picking a different place to measure from can significantly change the coordinates. If you use different datums in your GPS and on your map, you can end up in the wrong place.
- Determine the easting.
- The first number in UTM coordinates in called the easting.
- The easting refers to how far east you are.
- If you are using a map, look at the numbers found along the edge of the map that correspond with the UTM coordinates. The easting coordinates will be found along the top and bottom of the map.
- If you are using a GPS, the easting will be the first number when it is set in UTM mode.
- A change of 1 number in easting coordinates, for example 510,000 mE to 510,001mE, is a change of about 1 m (1 yard) on the ground. If you walk from 510,000 mE to 511,000 mE without changing your northing, you will have walked approximately 1 km (.62 mi.)
- Interpolate easting coordinates on a grid to determine an exact location.
- Determine the northing.
- The second number in UTM coordinates in called the northing.
- The northing refers to how far north you are.
- If you are using a map, look at the numbers found along the edge of the map that correspond with the UTM coordinates. The northing coordinates will be found along the right and left of the map.
- If you are using a GPS, the northing will be the second number when it is set in UTM mode.
- A change of 1 number in northing coordinates, for instance 510,000 mN to 510,001mN, is a change of about 1 m (1 yard) on the ground. If you walk from 850,000 mN to 851,000 mN without changing your easting, you will have walked approximately 1 km (.62 mi.)
- Interpolate northing coordinates on a grid to determine an exact location.
Tips
- The most common problem that people have when using UTM coordinates is that their UTM datums do not match. If you are having a problem when you are using UTM, the first thing you should do is check to make sure that all maps, books, and GPS systems you are using are set up in the same UTM datum.
- A plastic UTM grid read can be used with a map to very accurately interpolate UTM coordinates. However, care should be taken to insure the scale of the UTM tool matches the scale of the map - different scales between tool and map is another common problem which can lead to incorrect coordinates / plotting.
