How Accurate is a GPS Running Watch?

There are many times that I have been asked, just how accurate is a running watch with GPS? Can they really tell you how fast and far you are running? As a case study, we can look at two of the most popular GPS running watches, the Garmin Forerunner 305 and 405.

Both the Forerunner 305 and the 405 have an integrated, high-sensitivity SiRF star III GPS receiver. Honestly, I have no idea what this means. But I can tell you that they are both incredibly accurate.

The Garmin watches have a feature where they will tell you how many satellites they have located and tracking you while you run. On this same screen, it will give you an accuracy range. Typically, this range is between 10 to 20 feet plus or minus. This means that the satellites orbiting the earth know that you are within a 30 to 40 foot diameter circle. At worst case scenario, 40 feet would only take a couple of seconds to run so the watch would be off only by a couple of seconds.

After logging several hundreds of miles with a Garmin watch, I have found very little inaccuracies in its distance or pace. As I have run the same routes with the Forerunner, it will consistently beep on the mile markers in exactly the same spot along the route. On my regular 5 mile loop, I have learned to expect the beep signaling the start of my last mile as I am passing the third power pole on the right.

As another test, my running partner and I both wore a Forerunner watch for a 20 mile training run. As we finished the run, we found that the distances on the GPS watches were nearly identical. Over the course of 20 miles, there was less than one twentieth of a mile discrepancy between the two watches.

In short, the answer is that a GPS running watch is a very accurate measure of your time and distance. Garmin GPS watches provide critical information that can help you understand and analyze your training. The ability to track your pace, distance, heart rate, etc. gives you the tools to improve your running, get more out of every workout, and become a better runner. Click here to see more ways that you can maximize your performance by training with a Garmin GPS running watch.

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