GPS accuracy / distance calculation not accurate

[Nemodyne]

Fitbit app's ( Android App now 2.71) GPS distance estimation is no longer accurate (for a few months now). I would no longer recommend as a training aid for running. Details: I have a Charge 2 and use the Fibit Android App's GPS at least twice a week to track runs. The distance estimated for a run used to be quite accurate, then starting around February/March I noticed it now underestimates runs, which also kills pace/calorie etc estimates. I'm running marked trails and comparing to other peoples GPS, as well as old Fitbit records. Example 5 mile loop used to track as 5 miles, not 4.6-4.7 miles as it does now. To rule out my phone as the culprit I ran with both Fitbit and another app tracking simultaneously, and it couldn't be clearer (see picture below). Note: this trail is marked as 5.0 miles, and it took a little to start/stop the individual apps so I expect them to be a little different. Prior troubleshooting: I had deleted and reinstalled the Fitbit app 2 weeks prior. I have also run the week prior with only the Fitbit app tracking the run, no charge 2. I have also ensured the Fitbit app has all permissions and phone's GPS accuracy is set to high. I've also checked and the app records the start and stop location accurately, so that's not it. If I had to guess I'd say an update was made to the Fitbit app to decrease the frequency of GPS signal reading, probably to improve battery usage, and on even mildly curvy trails this leads to poor distance estimation. Bottom line this is not acceptable, what use is a fitness tracker that can't track anymore, especially when it was perfectly capable last year. Fitbit app left, other app right

Moderator Edit: Updated Subject For Clarity.

[RobertoME]

Hi there @Nemodyne, nice to see you again and my apologies for the late response. I was reading your feedback about the inaccurate distance using connected GPS with the Charge 2 after the new update. I can assure you the new update doesn't change anything about the functionality of the GPS. Nonetheless I will pass your comments to our team to look further.

There are a few key points significantly important to mention when is related to GPS. Note that the Connected GPS will never be an exact match with other third party apps measurements, as we are talking that each developer has its own unique algorithms.

Now, there are external factors that may have an impact in the accuracy of your GPS course. For this I would like to share with you this help article: Why isn't GPS working on my Fitbit device?

If this started happening recently, it would be recommendable too to reset your Fitbit app: log out from your Fitbit app and go to your phone settings. Access to the App manager option and look for the Fitbit app in your downloaded apps list. Once you are there, clear the app cache and data and proceed to "Force Stop" the app. Finish the workaround by restarting your phone. When your phone has initialized, go back to your app and try again.

Give it a try and if there are more updates, I will keep you posted.

[Nemodyne]

I tried clearing the cache and data and reinstalling the app. the problem persists. i checked the downloadable data from today's run and compared to one last year for the same track. today's was logged as 4.80 miles, the one in 2017 as 4.98 miles. The track is actually marked as 5.0 miles, so the measurement in 2017 was closer. I can confirm data is sampled every second in both runs, so the rate of GPS sampling is the same. The only thing I can think of is that the app's way of calculating the lines between gps pings must have changed. I think fitbit needs to seriously consider that other users are reporting the same issue...maybe run a few test engineers around a very curvy measured track, and see what the results are. Either that or give users an options to set the sample rate from every second to every 0.5 seconds when they desire high accuracy and/or battery usage isn't as valuable.