This is the clearest and most concise explanation on Youtube about the UTM coordinate system. We start with an overview of how the UTM system works, then you'll learn how to read coordinates from a map, how to plot coordinates onto a map, and we’ll finish with a few good mapping and smartphone resources.
Knowing to basics of coordinate systems is important for anyone using a map and GPS together.
There are two good reasons to understand coordinate systems:
1. If you need a rescue, you can tell 911 right where you are.
2. If you’re lost, and you have a GPS, you can plot the coordinates onto your map to get yourself unlost.
This video is part of our complete series from the Columbia River Orienteering Club on wilderness navigation and orienteering. See all the videos on our YouTube channel, or at www.croc.org.
====================
We’ll start with an overview of how the system works, then you'll learn how to read coordinates from a map, how to plot coordinates onto a map, and we’ll finish with a few good mapping and smartphone resources.
There are two good reasons to understand coordinate systems:
1. If you need a rescue, you can tell 911 right where you are.
2. If you’re lost, and you have a GPS, you can plot the coordinates onto your map to get yourself unlost.
Here’s why UTM is better:
• Easy base 10, metric system
• One way to write coordinates, not three
• Easy to determine coordinates from a map
• Easy to plot coordinates onto a map
• Easy to shorten / truncate
UTM coordinates are always given in a specific order: Zone, Easting, and Northing.
Remember high school geometry, and X-Y coordinates? UTM works in exactly the same way.
The Zone is one of 60 tall skinny rectangles that cover the earth.
The X coordinate or, horizontal axis, is called an easting.
The Y coordinate, or vertical axis, is called a northing.
Here's an example of a complete coordinate: 10 4587346 N 487349 E
UTM zones divide the world into 60 different tall skinny rectangles, each one of them 6° of longitude wide.
Now let's look at where the easting and northing coordinate come from.
The Easting is a value of 500,000 at the central meridian of the zone.
The northing is zero at the equator (northern hemisphere)
Another easier way to think of it:
Imagine a tall, skinny 1 meter grid centered over this zone.
The grid is 10 million meters tall, and 1 million meters wide.
The X-Y origin is the lower left corner of this tall skinny one meter grid.
So, easting values for a given zone begin at this 0-0 point.
Easting values increase as we move to the right, or east, from this point.
Easting values are always six digits.
Here we see a grid that's 1 km in size, increasing by 1 km as we move to the east.
Northing values are measured in meters north of the equator.
They increase as we move north.
Northing values (at least in North America) are always seven digits.
Here we see a grid that's 1 km in size, increasing by 1 km as we move to the north.
Okay, let’s see how this works on a simplified map.
What are the coordinates of point X?
Remember, the printed grid is 1 km.
Easting and Northern coordinates are often abbreviated on a map border by dropping the last three digits, and the numbers showing the kilometers are often printed in bold, as we see here.
First, let's look to the left of our point and find the closest Easting line.
Here, it's 611.
Second, look below the point and find the closest Northing line.
Here, is 4591.
Now, we estimate the location of point X to the nearest 100 meters.
It might help to imagine a grid of 100 meter squares covering the 1 kilometer square that contains point X.
Point X is just about midway between the 611 and the 612 Easting lines.
Because these Easting lines are 1,000 meters apart, halfway is about 500.
Estimating the Northing, it looks like point X is just a little bit above the midway point.
Again, because these Northing lines are 1000 meters apart, a little above midway makes it about 600 meters.
So, that gives us our final estimated coordinate of 611 500 E, 4591 600 N.
Hopefully, you now have a basic understanding of finding the coordinates of a point on the map.
Let's have a look at the flip side of that, which is plotting coordinates onto a map.
Step 1, get your UTM coordinates.
Step 2, change the last two digits to zero.
Step 3, mark the Easting line. You don't need to draw the entire line on your map. Usually just circling the number in the map margin is good enough.
Step 4, mark your Northing.
Again, circling that number in the map margin works well.
High Fives! You have found your position on the map to about 100 meters.
Of course, to do this you need a map that has a UTM grid printed on it. Most of the 7 1/2 minute maps printed by the US Geological Survey have UTM tick marks on the margins, but do not have a printed grid. Print topo maps for FREE at caltopo.com.