Things You'll Need
Instructions
Note the dilution of precision (DOP) of your current status on your GPS unit. The DOP is a measure of the ranging error of the GPS unit. Factors that can affect your device's accuracy include tree cover and hilly topography which interfere with the GPS unit's reception of satellite signals. Knowing the DOP figure gives you an idea of how accurate your calculation will be.
Set a waypoint at your current location. A waypoint is a user-defined point of reference. Make note of the coordinates. There are different coordinate systems. Use the GPS format of degree and minutes, displayed as DDD.MM.MMM. This system provides great accuracy with calculation, especially when dealing with relatively short distances.
Set a waypoint for the second location, noting the coordinates. Again, use the GPS format. You can set the default coordinate system on your device. Refer to the user manual for instructions.
Use the GPS to calculate the distance. From the second location, use your device to navigate to the first location. The GPS unit display will show the distance to the location. Bear in mind that this figure is "as the crow flies" and may not be an exact indicator of driving or walking distance.
Alternatively, use an online GPS calculator to calculate the distance. Enter the coordinates of the first and second location. Do not forget to indicate whether the longitude is east or west or whether the latitude is north or south. This information can be found with the coordinate display on your GPS unit.
Manually calculate the GPS distance. Calculate the difference between the two numbers. One decimal minute, 0.1 on your display, equals approximately 6.9 miles.
Use a topographical map to calculate GPS distances as another calculation method. Plot both points on the map, using the latitude and longitude grids on the sides of the map. Note that topo maps use a different coordinate system of degree-minute-second. Use an online calculator to covert from the GPS format.
Measure the distance between the two points with a ruler. On a map with a 1:24,000 scale, one inch on the map will equal approximately 24,000 inches on the ground, or 2,000 feet. As with the GPS unit, this figure represents an approximation. It will not reflect additional distances due to topography.