Reading and Mapping GPS Coordinates

GPS coordinates are incredibly useful both in the military and civil world – and are essential to modern society’s navigational and mapping systems. In this guide we shall look at how you can read and map GPS coordinates.

What are GPS Coordinates?

GPS is a navigational system that uses signals from satellites in space to help give exact coordinates to a GPS receiving device on Earth to specify an exact location.

There are currently 24 active and 3 back up satellites in space – all owned and run by the United States. By having a GPS receiving device you can connect to several of these satellites which will send down signal that are converted into GPS coordinates.

Reading and Mapping GPS Coordinates

How do you read GPS Coordinates?

At first glance GPS coordinates look like a jumble of numbers, however if you know what you are looking for they are incredibly easy to understand and read.

Firstly you need to understand where the Prime Meridian and International Date Line are located – these divide the Earth into East and West. As a general rule, the Americas and most of Africa are located in the West, whereas Europe and Asia are located in the East when in terms of GPS coordinates.

Then you need to divide the Earth into Northern and Southern hemispheres to help with the reading of GPS coordinates. This simply means that all areas north of the Equator are in the northern hemisphere and all areas south of the Equator are in the southern hemisphere. If, for example, you have the coordinate of N 40 degrees, this means that you are located on an imaginary latitude line 40 degrees north of the Equator.

If you have a coordinate of S 45 04’ this is a more exact coordinate that states you are just above 45 degrees south of the equator. If you see a minus sign on your GPS coordinate in place of the ‘S’ this  can also represent south. West can also be shown as a minus sign. North and East are always positive on GPS coordinates.

All GPS coordinates are given relative to the imaginary lines we have mentioned before – the Equator and the Prime Meridian and International Date Line. GPS coordinates to the west of the Prime Meridian (such as those in the USA) are represented with a W or a – sign. Whereas those to the east are given a positive number.

Reading GPS Coordinates

Difficulties in Reading GPS Coordinates

While we have given you a general method of reading GPS coordinates – there are four different forms in which GPS coordinates can be presented. This can make it difficult to understand the coordinates if you are not knowledgeable on all the types.

GPS coordinates use minutes and seconds to help establish more localized points between degrees. This can be presented in several ways such as 06’ 34”, 6 minutes and 34 seconds, 6.34 minutes or .104124 (number divided by 60). You should be aware of all the different ways that GPS coordinates can be represented.

As we mentioned earlier, some GPS coordinates will use plus and minus signs while others will use N, S, E, and W in their coordinates. It is important to become aware of all the different forms of GPS coordinates so you can understand any type.

Mapping GPS Coordinates

It is easy to map GPS coordinates – however be aware that not all maps are very accurate. You need to use maps that use local datum instead of global datum.

If you have a detailed map of the area you are covering then chances are it will be very accurate. Most maps will have latitude and longitude lines drawn onto them so using your GPS coordinates you can simply find the longitude and latitude values and draw your fingers together until they meet in the middle at a point.

This is the manual version; however those that are comfortable using GIS (Geographic Information System) programs can input GPS coordinates onto a computer where the program will simply plot the coordinates on a map for you. These programs however are very expensive and hobbyist explorers or those wanting to map GPS coordinates will generally use the manual way using a printed map.