tomtom spark 3 - distance accuracy

Reprovo Registered Users Posts: 1
New Traveler
edited January 24 in TomTom Sports

I just purchased the spark 3 and i ran a few laps over a known distance. I noticed that initially if i start running a few meters before the lap starting point, the distance for each lap was very accurate. Is there any reason that would be the case or just a fluke ?
I've only tested this twice so far so I really have no idea.


  • tfarabaugh
    tfarabaugh Posts: 16,943
    If you at running on a track that could be the issue. The nature of GPS is that each data point collected is only accurate to within 15-30m of your actual location. The watch collects the data points and then tries to figure out a route using them (considering that some points may overlap or duplicate). The watch then smooths the data to come up with the most reasonable route taken according to the algorithm it is programmed with. This is why every watch, even two of the same model, will come up with different distances, as they are collecting different GPS data. On a track, GPS does not do well as the constant turning throws off the readings - if you look at the GPS track you will see it often cuts off the turns.

    You also have to consider what is a "known distance". How was it measured and was that measurement accurate? Ultimately no GPS is 100% accurate but I find the TT devices are pretty good.

    I hope this helped answer your question. If so, please mark it as a solution so others can look for it if they have the same question.