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Accuracy of GPS tracking on mobile phone

Rob Henson
Rob Henson asked
Medium Priority
Last Modified: 2019-10-18
Recently been doing a lot of running training and been tracking my runs using a Fitbit Charge 2 to upload to Strava. Charge 2 only has connected GPS rather than built in so I have to carry my phone (Samsung S6) with me to get the GPS tracking.

I have noticed that on a number of occasions the tracking recorded is somewhat out of kilter with the route I know I took. If you're able, take a look at the Strava link below for an example.

Strava Activity

If not able to see the Strava link maybe the picture below will show the issue.
Strava map
If you zoom in on the route you can see for example the sections through Charlton Hayes and Catbrain are quite wiggly, those roads are virtually straight and I certainly didn't wiggle along it like a drunken sailor as the GPS track would suggest. Likewise in the top left part of the route, there is a section where it looks like I broke off the road into the woodland before coming back to the road; I didn't. There are other sections where the GPS track wanders away from the road that I know I took. Where it cuts corners I guess its because I lost GPS signal briefly and it has just joined the points where I lost and regained signal.

I know GPS is dependent on a number of factors, visibility of satellites etc, but this particular route was on a nice clear evening with very little cloud cover, there are sections through trees but some of those are more accurate than the open road.

I am wondering if it is to do with how I am carrying my phone while running. The two options I have are in a bum bag (fanny pack for US folks) or in a sport sleeve on my arm. I am inclined to think that the bum bag is more likely to cause issues as it is fully enclosed and then surrounded by other bits and bobs in the bag, carbo gel packs etc. The bum bag doesn't claim to have any sort of RFID protection.

The attached example was using the arm sleeve.

If I measure the above route on Google Maps it measures at 11.3 miles whereas the GPS track puts it at 11.9 miles. I realise that's not a massive discrepancy but would be grateful for any suggestions for improving the accuracy of the tracking.

Watch Question

KimputerIT Manager

Please know the recording app is also responsible, not just the GPS signal etc what you said earlier. That's because recording too much will slow down your phone, and burn the battery faster.
Please check the app for update speeds and accuracy settings. The higher, the more detailed, but also will drain your phone more. Most probably, the few updates along the road are the cause those wiggly lines.
Rob HensonFinance Analyst


I hadn't really thought about the intermediate stages.

I guess the Charge 2 is communicating with the Fitbit App on the phone which is also using the location tracker on the phone. The upload to Strava is only once it is finished.

For my next run I will see how accurate it is if I don't use the Charge 2 to instigate the tracking but use the Strava App to record directly.
Jackie Man IT Manager
Distinguished Expert 2019

How do you setup the GPS in your phone?


By default, your phone will use assisted GPS to determine your location.

Finally, if possible, use a dedicated GPS receiver instead of a mobile phone if you want to be accurate about your location.
Rob HensonFinance Analyst


As it happens I now have a new phone so will wait to see how the tracking goes on that.
Finance Analyst
New phone (Galaxy Note 9) is much more accurate and now carry it in a CamelBak style rucksack rather than in bumbag so maybe it gets less interference.

Thanks for all the info though.