# How to find bounding coordinates (lat/long) for UTM zones?

I want to error check incoming lat/lng points by checking if the point resides within the given UTM zone. (This would work for the data im using because sometimes there is a missing sign or lat/lng is reversed and the UTM zone can still be correct)

So given a UTM zone, how would you find the bounding coordinates for that zone?(Either the lat/lng for SW and NE corners or a range of lat/lng values for a given zone)

Also: Since I am supplied with both UTM and lat/lng I can convert both and cross compare as a way to validate incoming points but I thought it would be interesting to know how to calculate a UTM zone's bounding box in lat/lng form just given a zone (and possibly a hemisphere).

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did you check this on the web? dmap.co.uk/utmworld.htm UTM zones start at -180 degrees longitude and are 6 degrees wide, there is some "issues" near zone 32 but the math is fairly simple – Dan Patterson Mar 27 '12 at 21:37
You can also check which UTM polygon contains the point; see gis.stackexchange.com/questions/7532/source-for-utm-zone-file – Mike T Mar 27 '12 at 22:44
If it helps, here is a CSV that contains bounding boxes for UTM zones of North America. aaron-hoffman.blogspot.com/2016/04/… As well as a "point-in-polygon" calculation for a given WGS84 coordinate pair. – Aaron Hoffman Apr 19 at 17:14

## 1 Answer

I'm not sure what environment you're working in, but because UTM zones are referenced to a unique central meridian, the longitude of a point should be within +/- three degrees centered on the central meridian of your target UTM zone.

Regarding a projectable/renderable bounding box of a UTM zone, ESRI datasets that come with ArcGIS should contain a UTM zone shapefile, but you could also roll your own pretty easily. The northing coordinates will always be 180/-180, and simply walk your way through every 6th line of longitude, and there are of course 60 zones in the world.

You'd have to watch out for the exceptions Dan mentions in his comment as well as the polar zones which @whuber pointed out.

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You mean "within three degrees," not six. Note that polar zones are constructed differently (but may be of no interest). Also, to be complete, it's necessary to know that the central meridians are all congruent to 3 modulo 6: -177, -171, -165, ..., -3, 3, 9, ..., 171, 177 degrees. For longitudes in the range [-180, 180], a simple calculation of the zone number is `1 + Int((longitude + 180)/6)`. – whuber Mar 27 '12 at 22:47
@whuber yes you're right, I was assuming centered on the CM – WolfOdrade Mar 27 '12 at 22:56
Im computing the central meridian of the zone like so: `// Central meridian of zone \$zcm = 3 + 6 * (\$this->UTMGridZone - 1) - 180;` so I would check +/- 3 degrees from this number eh? Thanks for your help BTW. – cs_brandt Mar 27 '12 at 23:22