How Accurate Are Gps Pedometers?

A GPS pedometer can add a new dimension to your outdoor workouts. You can use it to measure your run and set training goals for improving your time. You can also use it to map your hikes and walks using its software or web interface. Several things can affect the accuracy of the unit, some of which you can control and others you cannot.

External Factors

Some factors exist which you cannot control and may impact the accuracy of your GPS pedometer. You will not get a good signal on your GPS if obstructions such as heavy tree cover interfere with your device's ability to receive the signal. The same results will apply in hilly or mountainous areas as well as urban areas caused by tall buildings. Your best accuracy will occur in areas where the area around you is open.

Measuring Your Stride

Your accuracy is also dependent upon the stride length which you enter for the GPS pedometer's preferences. Your stride is the distance you travel in two steps. For women, it is about 2.2 feet and 2.5 for men. You can determine your stride by walking a set distance, counting your steps as you go. Then, divide the distance by the number of steps you took. Some GPS pedometer will allow you to enter an exact figure. Some units however, have a drop box with only half foot increments. If you fall somewhere in between, your pedometer will not be precise.

GPS Accuracy

While GPS is a useful navigational tool, it has limits to its accuracy. Prior to 2000, GPS signals operated under "selective availability," meaning that they were intentionally degraded by the federal government for security reasons. GPS signal had an accuracy of within 100 meters. In May 2000, selective availability was lifted. While accuracy improved significantly, civilian-grade GPS units of any type are only accurate to within 10 meters. Units with higher accuracy are only found on professional and military devices.

Troubleshooting

To measure your GPS pedometer's accuracy, you can try a simple test using a known distance. You can walk a running track or measure a distance using your car's odometer. Then, walk the same distance wearing your pedometer and compare the results. If the figures are widely different, you can look at factors which you can control which will improve its accuracy. For example, clothing with metallic features may interfere with the GPS signal in the same way that trees would, especially on sleeves worn over your wristwatch unit. You can also verify that your stride length is correctly set.