Reading GPS Coordinates

How to Read GPS Coordinates

Reading GPS coordinates can seem a bit difficult for the untrained do to all those crazy numbers on display.

Learn How to Read GPS Coordinates

To really understand how to read GPS coordinates, you first need an introduction to the system of latitudes and longitudes. Don’t worry, it’s actually easier than it looks!

Latitude

Imagine looking at the earth in the typical way, with the North Pole at the top and the South Pole at the bottom. The lines of latitude are the lines that go from east to west. The main latitude line is the equator in the middle, and it’s designated as 0 degrees (0°) latitude.

At the topmost is the North Pole, and it marks the point known as 90 degrees latitude. So you can just imagine 90 lines of latitude from the equator to the North Pole, and each line will denote an increase of 1 degree latitude.

Since this goes up to the North Pole, this is marked as 1 degree N. You can be in a city that’s located 15 degrees N, or 30 degrees N, and so on.

The same goes south of the equator all the way to the South Pole. This time, you mark the first degree of latitude from the equator as 1 degree S. The further south you go the larger the number gets.

So you can be at 15 degrees S, and when you go further south you can get to 30 degrees S, and so on up to the South Pole.

Longitude

This time the lines are vertical, stretching from the North Pole to the South Pole. The Main Line of longitude is the Prime Meridian, which is basically the vertical line that goes through London.

When this line was drawn in the late 1880s, Great Britain was the most powerful nation in the world, so they decided that their capital would denote the Prime Meridian.

Since a circle is 360 degrees, you can go up to the other side going east in degrees up to 180 degrees (180°). As you go east, you can denote your location as 15°E, 30°E, and so on up to 180 degrees.

You can go west and mark your location from the Prime meridian the same way, except this time you denote the location as 15°W, 30°W, and so forth.

With the two lines of latitude and longitude, you can find the intersection that denotes your location on the world map. So you can be 15°N and 1°E, and that’s basically the country of Niger in Africa.

The problem is that if you want to be exact, you need to denote the spaces between the basic lines of latitude and longitude. Many specific locations and cities aren’t found in these basic degree lines, so you need to use fractions.

DMS

This stands for degrees, minutes, and seconds. From 1° to 2°, you divide the space into 60 minutes. Then every minute you divide it into 60 seconds

New York City in this format is located at GPS coordinates 40° 43′ 50.1960” N and 73° 56′ 6.8712” W. You read that out loud as 40 degrees, 43 minutes, 50.1960 seconds north, and 73 degrees, 56 minutes, and 6.8172 seconds west.

DMM

This time, instead of degrees, minutes, and seconds you get degrees and minutes only, with the minutes expressed in decimal terms. So in this case for NYC, you get 40° 43.8366′ N and 73° 56.11452′ W. That’s 40 degrees and 43.8366 minutes north, 73 degrees and 56.11452 minutes west.

In some cases, instead of using north, south, east, and west, the coordinates use positive numbers for north and east and negative numbers for south and west. So for NYC, that can also read as 40° 43.8366′, -73° 56.11452′.

Though this seems simpler, this system isn’t really all that popular. Either people use the traditional DMS, or they simplify everything through the DD (decimal degrees) system.

DD

The decimal degrees system don’t use minutes and seconds, as those figures can make coordinates overly complicated. With this system, everything is just a matter of degrees expressed in decimals. In the case of New York City, you then get the simpler 40.730610° latitude and -73.935242° longitude. In fact, in some cases it’s just presented as 40.730610, -73.935242.

The first number always denotes the latitude (north or south) while the second number is the longitude (east or west). The positive numbers again denote north and east, with the negatives denoting south and west. So in the case of NYC it’s located 40.730610 degrees north and 73.935242 west.

Final Words

Of course, just getting the numbers won’t really help us ordinary folks who don’t have a mental map in our heads to make sense of these coordinates. These GPS coordinates make a lot more sense when you superimpose them on a map.

With decimal systems for the seconds or for the degrees, you can specify the location of not just a city, but a neighborhood or even a single shop. If you are interested in more of the history and technical data behind GPS Coordinates there is a great Wikipedia article that goes over the global positioning system in depth.

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