Calculating the eastern and western boundaries of a UTM is very straightforward. Developed by the U.S. Army, the Universal Transverse Mercator (UTM) is an international plane (rectangular) coordinate system. In the coordinate system, the world is divided into 60 zones of 6 degrees longitude. Each zone extends 3 degrees east and west from its central meridian and are numbered consecutively west to east from the 180-degree meridian. Transverse Mercator projections may then be applied to each zone.

**Difficulty Level:** Easy ** Time Required: 1** minute

Here’s How:

- UTM zones are all 6 degrees wide and increase from west to east starting at the -180 degree mark.
- Calculate the eastern boundary of any UTM zone by multiplying the zone number by 6 and substract 180.
- Subtract 6 degrees to obtain the western boundary.
- Therefore to find the eastern boundary of UTM zone 11: Eastern boundary of zone 11 = (11 * 6) – 180 = -114 degrees.
- Western boundary of zone 11 = -114 – 6 = -120 degrees.

Note that there are some exceptions to the ‘all zones are 6 degrees’ rule, especially in northern Europe – check the map at http://whatutmzoneamiin.blogspot.com/ for more details.

Eric is asking how to determine the zone boundaries for a given UTM coordinate for which the zone number is unknown. This requires some math, considering the distortion of the projection at the equatorial and polar regions. All the basic equations you need are located here… rotate the pieces put the puzzle together – it’s good exercise for your brain!

http://www.uwgb.edu/dutchs/UsefulData/UTMFormulas.HTM

Eric, you can calculate max X and Y for a particular UTM zone, these numbers will be the same across all UTM zone, except non-standard ones. The results will also depend on which geo ellipsoid you are using.

To lookup zone, based on the geodetic coordinate, you can use this online tool:

http://www.apsalin.com/utm-zone-finder.aspx

Please clarify the question, what are you trying to find, what do you been under the boundaries – is it max/min values of X, Y?

This is well and good but how do you do it the other way? How do you calculate the boundaries of a UTM Zone given a UTM coordinate?