The UTM, Universal Transverse Mercator, is a metric system of coordinates. Maps overlayed with the UTM grid provides (1) an easy reference for estimating and or measuring distance and 2) the north-south lines of the grid provide a convenient reference for the compass.
You can use the UTM coordinate system for any references that you would like to make, particularly with a GPS unit.
Here is a brief example of how the system works. UTM coordinates are given in two parts. The first part, left to right or west to east is called Easting. The second part, down to up or south to north is called Northing.
Reading and Understanding UTM Coordinates:
The UTM coordinate for the red dot indicating WPC? is
Zone 11 0643772 / 3992092.
0643772 is the Easting.
3992092 is the Northing.
Zone 11 is given in the margin data of the map and beyond the scope of this map. Let's ignore it.
The numerals 6 (from the easting which I write as 06 to keep my bookkeeping straight) and 39 (from the northing) refer to a 10,000 meter area beyond the scope of this map. Let's ignore these numerals.
The last numeral, 2, in both the easting and northing is to 1 meter accuracy. Let's ignore this numeral.
I will underline the numerals that we need to concern ourselves with:
E 0643772 / N 3992092
I also put an E before the easting and and N before the northing to remind myself to read 4377 from left to right and 9209 from down to up. In other words, the entire coordinate is read right and up. The coordinate is read right and up from the lower left hand corner of each increment of grid. Again...
0643772 / 3992092 - reading right and up, refers successively to the lower left corner of smaller and smaller, and therefore increasingly more accurate squares. The numerals, 4377 / 9209, is a coordinate to 10 meter accuracy or 32.8 feet which, is close enough for me while walking, biking, or paddling with a map and compass. If you're geocaching with a GPS device, you may desire the 1 meter accuracy of the additional numeral or 43772 / 92092.
0643772 / 3992092
43 and 92 refer to the lower left corner of this 1000 meter square:
Or, 43/100’s to the right and 92/100’s up in the 10,000 meter square defined by the numerals 06 and 39.
0643772 / 3992092
7 and 0 refer to the lower left corner of this 100 meter square:
Or, 7/10’s to the right and 0/10's up in the1000 meter square defined by the numerals 43 and 92.
0643772 / 3992092
7 and 9 refer to the lower left corner of this 10 meter square:
Or, 7/10’s to the right and 9/10’s up in the 100 meter square.
Plotting UTM Coordinates:
I would use the following procedure to plot the UTM grid coordinate, Zone 11 0736343 / 3985400. The information Zone 11, 07, and 39 tell me I am on the right map. I do not need this information to plot. I will also ignore the last numerals of both the Easting and the Northing. The coordinate I will use to plot is E 3634 / N 8540. This will get me to within 10 meter accuracy.
Note: The blue square in this image is the 10 m square described below.
1000 meter square
100 meter square
10 meter square
For a plotter, I will use a corner of the baseplate of my compass which I've marked on waterproof tape with 100 meter hash marks.
(1) I find the correct 1000 meter grid square by taking 36 from the Easting and 85 from the Northing.
(2) I mark the lower left hand corner of that grid square.
(3) I then use 34 from the Easting and 40 from the Northing.
(4) I move the corner of my plotter from the lower left corner of the grid square, 340 meters to the right and 400 meters up.
Example: If someone is reading me the coordinates, they will call out "Grid Square 36 / 85". I will then relay back "Check 36 / 85" while I mark the corner of that square.
They will then call out "Right 340 meters and up 400 meters". I will then relay back "Right 340, up 400", and announce, "it appears to be the intersection of a Transmission Line and a 4WD trail".