Accuracy of distance run.

bigmazungo Registered Users Posts: 4
Apprentice Traveler
edited January 24 in TomTom Sports
Hey all hope there is someone out there that can help me out with what is becoming a very irritating issue with my watch.

I run the same route every week but my Tom Tom sport has given me different distances each time. it was 6,25km last week but forntje same run today it assesses that I had run 6.11km. If the distance measures are out of whack I worry that the other measures may be similarly dubious.

Anyone experienced the same of who can point me to a resolution or peace of mind?


  • tfarabaugh
    tfarabaugh Posts: 16,932
    This is totally normal. 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. Every time you run that route you are collecting different GPS data is the route is slightly different. A variation of 2%-3% is considered totally acceptable in the industry.

    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.
  • bigmazungo
    bigmazungo Registered Users Posts: 4
    Apprentice Traveler
    Well what do ya know -- distance via GPS data an imprecise science. Should have guessed it in my far too confident resiling to the omnicompetence of technology. Thanks a lot! I've come across a number of your posts and they are as lucid as they are immensely helpful.