Charge 3 not tracking distance accurately

[Beanieg4]

I use my Charge 3 synced to a Samsung phone to track my on road runs.  It will track the correct route I take, but the total km are quite significantly wrong when compared to the same route calculated in Google or MapMyRun.  Eg a 5.5km run on Google was logged at 4.5km in Fitbit this morning, and you can see from my km split times that it is portioning the entire remaining distance / time into the last km (average split 8'10", last 0.5km split time 9'49").

Moderator edit: updated subject for clarity

[MarreFitbit]

Hi there @Beanieg4, welcome to the Community Forums. Thanks for the details provided about your Charge 3's accuracy and for taking the time to compare it in Google or MapMyRun. Nice way to go!

While reading your post I was wondering if the mobile device you're syncing with is included in our list of supported devices? You can see the list at: Which phones and tablets can I use with my Fitbit watch or tracker?

Please keep in mind that when a device is not supported we cannot guarantee its functionality with the Fitbit app. It might work at a certain time and then it can stop working out of nowhere after an update. This is because the app is not optimized to that device and any change could impact the performance. 

Fitbit devices calculate distance by multiplying your walking steps by your walking stride length and multiplying your running steps by your running stride length. We estimate your stride lengths using your height and sex. Track one or more runs using on-board or connected GPS, we evaluate that data to automatically update your running stride length. For best results, run at a comfortable pace for at least 10 minutes.

If you prefer to measure your walking and running stride lengths yourself and enter them manually, see How do I measure and adjust my stride length?

Note that when you're tracking an activity with GPS, Fitbit calculates your distance using GPS data rather than steps. If you begin moving before you get a GPS signal, the tracker will calculate distance using steps and stride length as described above until a GPS signal is found.

Keep in mind that your device uses your step count to calculate distance until it finds a GPS signal. In this scenario, your total distance calculated for the workout may be slightly less accurate than if GPS data were available for the entire duration. For more information, see How accurate is GPS?

After reviewing this factors, please go for another activity and see if the distance improves. 

Let me know how it goes.

[Beanieg4]

Hi Marre,

Thanks for your detailed email. I'm on a Samsung A50 with Android 9, so not
a supported device but a supported OS.

I should add though that I've never had an issue with syncing my phone,
this issue appears to be entirely to do with how distance is calculated
from a GPS route.

>From looking a little closer you can see on things like the pace graph that
my pace is consistent throughout the run, but in the km split tabs the pace
for the last 'partial km' contains all the remaining distance as my pace is
showing as significantly higher (I'd attached screen grabs to illustrate
but dont know how).

Also, if this is an app/device compatibility issue then why do I see it
replicated when I log into fitbit online too?

Thanks for your help