Displayed lap times on wrist vs. MySports / how accurate is the Spark 3 GPS supposed to be?

ChetK105 Registered Users Posts: 1
New Traveler
edited January 24 in TomTom Sports
This is a two part question. First, I've noticed that mile split times displayed on my wrist (1.0 mile Laps workout) often differ by several seconds from the "final" results when I finish the workout and sync with MySports.

Unfortunately I can't post an example of this but it leads to another question - how accurate is the Spark 3 GPS supposed to be? I run the same path out-and-back 9 out of 10 days but the mile markers can vary quite a bit, sometimes +/- 100 feet.

I know being in the city complicates things and you can't expect perfection but it does seem off. Or is this just what you get?

Pic below, and here's a link to the workout. The lap time and mile pace also don't quite match up, even though I set lap distance to 1.0 miles.



  • tfarabaugh
    tfarabaugh Posts: 17,004
    The times on MySports have smoothing and pause detection factored in so they will not match the watch exactly. A variance in distance between activities is totally normal. The nature of consumer grade GPS is that each data point collected is only accurate to within 15m-30m of your actual location and it is a different data set each time. The watch collects the data points and then the website tries to figure out a route using them (considering that some points may overlap or duplicate) and a corresponding speed and distance. The website smooths the data to come up with the most reasonable route taken according to the algorithm it is programmed with. Every watch, even two of the same model, will come up with different distances and speeds, as they are collecting different GPS data.

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