Universal Transverse Mercator (UTM)
Transverse Mercator (UTM) coordinates define two dimensional, horizontal, positions.
- UTM zone numbers designate 6
degree longitudinal strips extending from 80 degrees South latitude to 84 degrees North latitude.
- UTM zone characters
designate 8 degree zones extending north and south from the equator.
- There are special UTM zones between 0 degrees
and 36 degrees longitude above 72 degrees latitude and a special zone 32 between 56 degrees and 64 degrees north latitude.
Shorthand for UTM Coordinates
Most land navigation
activities focus on a very small portion of the globe at any one time. Typically the area of interest to an outdoorsman is
less than 20 miles on a side. This focus on a small area allows us to abbreviate UTM coordinates.
The zone information
and the digits representing 1,000,000m, and 100,000m are dropped. The 1m, 10m and 100m digits are used only to the extent
of accuracy desired.
A GPS unit might read
10 S 0559741
a notation similar to the one found on a USGS topographic map, this would be written as:
Zone 10 S 559741 mE. 4282182
An abbreviated format for the same coordinates would look like:
a 1000m by 1000m square.|
a 100m by 100m square.|
a 10m by 10m square.|
a 1m by 1m square.|
The 100m abbreviated format, 597 821, and the 10m abbreviated
format, 5974 8218, are the most commonly used.
Notice that the easting is reported first, followed
by the northing. Remember the phrase "read right up" to help you remember to read the easting from left to right,
followed by the northing from the bottom up.
Also notice that when you abbreviate coordinates you should not do any
rounding. 0559651 becomes 596 not 597. This ensures that your position
is still within the reported square. As accuracy decreases, the square gets bigger.
to Know the Metric System
If the metric system gives you heartburn, here are a few tips
to help you out.
| The Truth|
(to within 3 or 4 significant digits)
| What you can remember|
(You'll be about 10% too short.)
|= 3.280 feet|
= 1.094 yards
|~= 3 feet|
~= 1 yard
|~= 100 yards|
~= length of a
|= 1 kilometer|
= 0.621 miles
~= 5/8 mile