Operating a GPS for backcountry or geocaching use is quite simple after a few minutes of experimenting with a device and following some simple GPS instructions like those included in this article. This is one of a series of articles we have on our site about GPS usage; see below for a complete listing of our GPS how-to articles.

This article discusses how to change measurement and unit settings on a GPS device and why and when you might want to do so. We often use a basic Garmin eTrex unit as our go-to example, but all GPS units function in very similar ways and have similar features. Before you start with these instructions, learn which keys, buttons or menu selections activate the following basic functions on the GPS you're using:

• Move between pages or menu screen - Usually a button labeled "Page". Like choosing between open programs or tabs on your computer screen.

• Scroll within choices on a page - this may be a "rocker" button or two "up-and-down" buttons, similar to the function a mouse or cursor movers does on a computer.

• Select a choice - usually a button that says "Enter". Serves the same function as the enter key on a computer or "OK" on a smartphone.


There are a number of unit and measurements settings you might want to change on your GPS. Most commonly, it's done to match the GPS unit's settings with a paper map, to make sure each is using the same coordinate system - latitude/longitude or UTM for example, or to match the "Map Datum". We won't get in to the details as to how these coordinate systems differ, but just know it is important that your GPS and map do match.

Shuffle thru the page options on your GPS and look for a "Main Menu" or Home page. Scroll down to the menu option named "Setup" or "Settings" and select it. Then find the sub-option labeled "Units", and then look for the option for "Format" or "Positioning Setup". Now adjust the options from a drop-down list that matches your general preference, or more important, matches the format with the paper map you are using. Typical popular choices include latitude/longitude expressed as degree/minutes/seconds or degrees/decimal minutes, and UTM. Look on the sides of the map or map legend to see how the map is setup. Using the wrong format setup can lead you astray.

Less important, but a change that can impact accuracy, is to change the Map Datum on the GPS to match the map. This is typically in the same menu area as the coordinate formats. There are dozens of options, but look for common choices such as NAD27; WGS84; or NAD83. A good map will state its Datum basis in its explanatory legend.

We have a nice library of how-to articles on this site. If you rent a GPS from LowerGear, we will also include a print or online user guide with full details on how to use it. We are also available to assist you over the phone. Links to our other articles in this series follow:

Our GPS Overview page
How to Mark a Waypoint with a GPS
How to Manually Enter a Waypoint Coordinate into a GPS
How to Navigate to a Waypoint with a GPS
How and Why to Change Map Orientation on a GPS
How to Record a Track of Waypoints on a GPS
How to Use a GPS to Find Your Location on a Map
What does WAAS Mean for a GPS
Using a GPS for Geocaching

See all of the GPS navigation and geocaching rental gear we can deliver to you for your next back-country, geocaching or driving adventure!

We'll ship your rented GPS unit direct to your home before your trip, or to any other convenient location. Or, you can pick up the GPS at our backpacking and camping retail store in the Phoenix area if your travels are nearby. After your trip, just package up the rented GPS back into the same box we shipped to you, use the prepaid return label, and drop off the rental gear at the most convenient shipping point used by our carrier - there will be many options in every city in the US.

If we're shipping rental gear to you, order far enough in advance to allow for a few days of transit time. Note that you are not charged rent during these transit days. We can get GPS rentals to you in anywhere in the US in 5 business days or less via UPS Ground, and expedited shipping methods for quicker deliveries are available. For more information, call us at (480) 348-8917 or stop by our outdoor retail store in Tempe, Arizona.