The Most Accurate GPS Watches! (Scientific Review)
In a Nutshell
Garmin and Coros watches delivered the most accurate GPS tracking, averaging just 2 m apart and staying closest to the overall average track, while Polar watches showed the most signal noise and deviation. Suunto performed moderately, with the Race 2 outperforming the Vertical 2. For the most reliable GPS performance during running or hiking, choose Garmin or Coros over Suunto or Polar.
These notes were generated by AI and may contain inaccuracies.
A marathon was run with eight top-of-the-line watches to test GPS tracking performance: two Garmin watches, two Coros watches, two Suunto watches, and two Polar watches. The watches tested included the Garmin Forerunner 970 and Forerunner 570, Coros Pace Pro and Pace 4, Suunto Race 2 and Vertical 2, and Polar Vantage V3 and Grit X2 Pro. All watches were carried during the 42 km run on the same track in Vienna where Kipchoge ran his first unofficial sub-two-hour marathon.
The total distance tracked varied between brands. Coros devices recorded approximately 43.33 km, Garmin recorded 42.4 km, Polar recorded roughly 42.7 km, Suunto Race 2 recorded 42.26 km, and Suunto Vertical 2 recorded 42.59 km. The average distance between Coros and Polar predictions was 400-500 m apart. The runner planned to run until all watches showed at least marathon distance plus 100-200 m wiggle room, ultimately running until Coros showed the lowest numbers.
Polar watches showed more signal noise, with the Vantage V3 deviating significantly and the Grit X2 Pro running slightly ahead. This instability resulted in extra virtual meters added to total marathon distance. The increased distance could result from watch unreliability, suboptimal running lines, or differences in how marathon organizations measure distance.
Within-brand consistency was measured by average distance between paired watches. Garmin and Coros showed 2 m average distance between their devices. Suunto and Polar, especially Polar, showed greater distances between their paired watches, indicating more signal noise.
Average distance was calculated between each watch and all other watches across the entire track. Garmin and Coros devices were highly consistent with each other, with the Coros Pace 4 and Forerunner 970 averaging 2.12 m apart, and the Pace Pro only 1.93 m from the Forerunner 970 track. Polar Vantage V3 showed the biggest discrepancy with all other watches, including its own brand mate. Suunto Race 2 performed reasonably well while the Vertical 2 struggled more. The close agreement between independent brands Garmin and Coros suggests these produce cleaner GPS signals.
Average GPS track was calculated across all eight watches, then each watch's distance to this average was measured. The Vantage V3 had the biggest deviation, followed by the Grit X2 Pro, then Suunto Vertical 2, Suunto Race 2, with all Garmin and Coros devices showing minimal deviation.
The same test was repeated during a mountain hike with slower exercise in a different environment. Polar appeared reasonably consistent, Garmin performed adequately, while Suunto showed more deviation overall. Differences were smaller than during running, possibly due to fewer obstructions and less foliage.
Within-brand distance measurements during hiking showed Suunto with the largest distance between their two watches. Garmin, Coros, and Polar performed similarly with distances over 3 m, indicating GPS tracking was more challenging in mountains than in the city.
Average GPS track calculations for hiking showed much more consistency between brands with no clear standout performer. Suunto had the hardest job while Garmin, Coros, and Polar performed similarly. Brand-to-brand differences showed Suunto standing out while others remained consistent with each other.
Results between hiking and running tests were not exactly consistent due to different circumstances. Based on all testing and other device experience, Garmin or Coros devices are recommended for best GPS tracking. In most situations, any brand will serve adequately, but for absolute best tracking and most solid reliability, Coros and Garmin are recommended. Suunto and Polar are not bad but may fall slightly behind in GPS tracking performance.
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