UTM Zone Calculation for Dummies

UTM Zones of North America

It's sad to say, but the internet has made dumbasses out of just about all of us, even (occasionally) the staff of the Antisocial Network. As a general rule, however, people around here are a little more aware of what's going on in the world writ large than are the likes of eHowian Nick Botero. Nick, despite having completed coursework for at least two college degrees, apparently never learned how to think. We base that observation on his rather useless answer to some poor schmuck wondering "How to Determine the UTM Zone" at Synonym.com.

It being eHow.com, Botero had to start out by explaining what UTM zones are. He did fairly well, although – like most of his fellow freelancers at eHow – it's pretty clear that he had no earthly idea why,

"There are 60 UTM zones across the earth's surface..." Not only did he not know why (to reduce distortion in the east-west direction), he also seemed unaware that you can make a case that there are 120 zones: sixty in the northern hemisphere and sixty in the southern. We can let that slide, though, because we have bigger fish to fry with Nick's post. According to him, you have to surf the internet to one of two internet sites to determine the UTM zone. After determining the latitude and longitude of the "target location," you must do one of two things:

• "Consult the DMAP UTM grid zone map, available online, to visually determine the UTM zone ...
• "Use the National Geodetic Survey's online conversion tool for Geodetic to UTM coordinates to convert the latitude and longitude..."

Heaven help the poor schmuck who doesn't have an internet connection, eh, Nick? Well, Heaven is here to help. Here's how you can determine the UTM Zone of any pair of lat-long coordinates, and you don't even need a computer. If you can remember how to do simple arithmetic with pencil and paper, you don't even need a calculator!

1. Start with a lat-long location, say, 44.46N, 110.83W – near Old Faithful in Yellowstone National Park
2. Add 180 to the longitude. By convention, west longitudes are negative, so the answer is -111 + 180 = 69
3. Divide the sum by 6: 69 / 6 = 11.5 
4. Round the answer up to the next whole number: The location is in UTM Zone 12N (because it's north of the equator)

Got that, Nick? No one needs a computer, mobile device, or internet connection to determine the UTM zone. Only a Dumbass of the Day would think otherwise.

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