Home / Advanced Backpacking Skills / The Universal Transverse Mercator (UTM) Grid System by Blake Miller

The Universal Transverse Mercator (UTM) Grid System by Blake Miller

Planning a Hike
Planning a Hike

Universal Transverse Mercator (UTM) is a grid system that describes a person’s location in the backcountry.  It is wonderfully simple to understand and use because:

  1. It is intuitive –  it’s concepts can be understood quickly
  2. It can be easily self-taught
  3. Young hikers grasp this system easily
  4. A location on a map can be quickly determined. 
  5. It is a selection option for Global Positioning System (GPS) receivers

Because of its simplicity, UTM is quickly becoming the principal grid system for hikers, hunters and Search and Rescue (SAR) teams nationally.

A navigation grid is a reference system developed by cartographers that can be used to plot a geographic position on a map.   There are many grid systems available for use such as Latitude and Longitude and Universal Transverse Mercator (UTM).  Many countries have their own national grid system.  The UTM system is just like a Cartesian Grid.  For example, the grid position below is just 2.2 units over and 2 units up.

Cartesion grid
Cartesion grid

Think of a grid as a series of defined squares on a map (see below.)

A grid is a series of squares on a map
A grid is a series of squares on a map

Cartographers have developed coordinates that are associated with the black grid lines.  Together, these components define location on a map.  The UTM grid lines form a series of equal squares on a map.  On a USGS 7.5’ minute topo map (scale 1:24,000), the spacing between the grid lines is 1000 meters (1 kilometer.)

The coordinate values are known Easting’s (vertical lines) and Northing’s (horizontal lines.)

The coordinate values are known Easting’s (vertical lines) and Northing’s (horizontal lines.)
The coordinate values are known Easting’s (vertical lines) and Northing’s (horizontal lines.)

Notice how the Easting values increase moving from left to right and Northing’s increase from bottom to top.  Coordinate values are always positive.

A key component to UTM grid is the identification of zone.  The earth is divided into 60 zones.  Every location will have a zone identifier.  On the map above the zone is linked to the Easting value and is the first set of numbers.  In this case the zone identifier is the number 10.  GPS receivers display the zone value linked to the Easting, see below.


Every location will have a zone identifier.
Every location will have a zone identifier.

The letter “T” seen above is a secondary, horizontal (east-west) identifier.  I personally pay little attention to it in my backcountry trips.

All USGS maps identify the zone in the title block at the bottom left of the map.  Note that on some commercial maps the UTM zone identifier may not be in the title block and can be hard to find.

The UTM coordinate can now be refined to a meter.  Again the spacing between the grid lines is 1000 meters (1 kilometer).  On the maps above, the tick marks between grid lines are in increments of 100 meters.  The hiker can then interpolate the distance between the tic marks.   For example:

  1. A standard grid line coordinate might be 10 6 04 000. (The three zeros to the right are units of hundreds of meters.)
  2. A position 250 meters east of 10 6 04 000 would be expressed as 10 6 04 250.
UTM Location example
UTM Location example

The position of the large X on the map above would be described as:

10 5 25 270 East (the green line)

47 91 180 North (the red line)

The final three places will always be expressed (10 5 25 270 East.)  The value 2 is in units of hundreds, the 7 is in units of 10 and the 0 is in units of 1’s.   Thus, 50 meters would be written as 050.  Otherwise, it could be considered as 500 meters instead of 50 meters.

Every point on a map (e.g., a mine, an intersection, a camp site, etc) can be described using UTM coordinates to the accuracy of one square meter.

I recommend consider carrying a small plastic ruler or other suitable straight edge when accuracy is important.  For general hiking and backpacking, one can quickly estimate a current position in the backcountry without other map tools.

UTM coordinates of a destination taken from a map can be easily saved on a GPS receiver.  For example, to do this the hiker “marks” a waypoint and then moves the backlit bar (yellow shaded area) from “save” to the “location” data field.  The “location” data field is then edited per the receiver’s instruction manual.

GPS Waypoint
GPS Waypoint

A fine reference for more practical information about UTM grid is Lawrence Latham’s book GPS Made Easy.  Chapter 5 has an easy to understand tutorial on this grid system; that’s how I learned it.

About Blake Miller

Blake Miller received significant hands-on navigational training during his 20 years of service in the US Navy.  He has taught map and compass, GPS and wilderness survival classes in Central Oregon since 1998.  As a part-time faculty member at Central Oregon Community College, he currently teaches land navigation classes to Natural Resource students.  He has been an active member of the Deschutes County’s Search and Rescue (SAR) team since 2009.   Blake is also a featured speaker at regional SAR conferences, Sportsman Shows, and Cabelas. His articles have been published in several national magazines.  Blake can be contacted through www.outdoorquest.biz.

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  1. Here are some important points for anyone who hasn’t used UTM before:
    1. You use this coordinate system instead of latitude and longitude because it’s so much easier. Therefore, you have to go into the setup menu of your GPS and change “coordinate system” to UTM from Lat/Long.
    2. Another thing to check in Setup is that the datum matches your map. It’s printed on the map somewhere and in the US will be either NAD27 or WGS84.
    3. Don’t worry about what alphabetic zone you are in. Unless you drove to a trailhead in the wrong state, you will be in the right zone.
    4. A nice tool to easily plot your position on the map is the C-THRU UTM plotter, which is a clear plastic grid that is much faster to use than a ruler. However, it doesn’t work for all map scales.

  2. One additional point – it’s a great argument for going metric! It’s a kilometer grid and if you think metric then you can read distances right of the map. I’ve found it helpful when sort of bushwacking because your gps grid tells you exactly how far off a N/S or E/W line you are in meters.

  3. I’m trying hard to understand how this is useful for navigation, but missing something. If I use a GPS, the GPS will show me where on the map I am, and will also tell me what my coordinates are — I don’t have to enter them. If I’m navigating with map and compass, then magnetic north lines on the map are the most useful, or I can just adjust my compass for declination — but I really don’t need the UTM or lat/long coordinates. Perhaps if I only had map & compass, and a phone, I could tell rescuers what my UTM coordinates are, but other than that I don’t see how the UTM system is useful for navigation.

    • Coordinate systems like this are really useful if you do a lot of cross-country navigation off trail or in extremely rural areas. Its really handy to look at the map and be able to tell that you are 2 kilometers from your destination by looking at the major gridlines, without having to measure it out on a ruler. The subtext here is that a GPS is good for pinpointing your location but pretty lame when figuring out where to go next or to stay on the right bearing. You really need to use a GPS together with a compass and map.

    • Jeff,

      There are two main reasons for backcountry travelers to learn about UTM coordinates.
      One assisting a rescue, and two, getting un-lost.

      1) if you need a rescue, you can tell 911 / SAR your exact location. If you have cell coverage, you can relate coordinates with your phone or text. If you don’t, you can hopefully write them down and send someone out for help. Either way, it takes the “search” out of search and rescue, and probably means you’re going to get help much faster.

      2) Say you are lost, and have a map with a UTM grid and a means to get your UTM coordinates (GPS or smartphone). If you can get your coordinate, you can then plot your position on the map and you’re not lost anymore.

  4. The letter “T” seen above is a secondary, horizontal (east-west) identifier. I personally pay little attention to it in my backcountry trips.

    ===>No it is not. Rather, it is the vertical (north-south) latitude band, which together with the zone identifier of 10, designates the “grid zone”.

    ==>The writeup doesn’t explain the “6” in an ‘easting’ of, for example, 10 6 04 000. It’s the hundreds-of-kilometers place. In other words, this easting is specifying 604.000km east in Zone 10.

  5. If your a surveyor in the IK, then this system is well known to all walkers, and all of the construction industry, for setting out.

  6. Sorry for the late reply to this thread.

    One thing often left out of discussions of UTM coordinates is what happens when a zone boundary crosses the area you are traveling through. At that point, some of the advantages of UTM disappear. At a zone boundary you have two grids that meet at an angle. How big that angle is depends on your latitude, here in Alaska it is fairly significant. Also, your False Easting values make a huge jump at the zone boundary.

    The UTM grid works well when you are out in the middle of a Zone, but can be somewhat of a hassle when operating around a zone boundary.

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