Connected GPS seems to record short

[MrSausages]

Hi,

I use my Blaze to record activity while running.  I connect to a Samsung Galaxy S7 which I wear on an arm strap on my upper left arm.  I have noticed over the past year or so that my runs are constantly recorded slightly shorter than people I run with.  For example, I recently ran a half marathon.  The people I ran with, using different devices, all found that their run was at or just over official half marathon distance.  Mine came in at 20.7km, just short of official distance.  I run a 5k run most Saturday mornings (parkrun).  Although most people record the distance at about 4.8km, my blaze with connected GPS on my Samsung phone records at 4.6km.

Is there anything I can do to recalibrate something?  Does the stride length setting affect this (mine is set to automatic)?

Sadly I don't know anyone else who uses connected GPS on the Android app, so I can't compare like with like.

Any thoughts would be greatly appreciated.

Many thanks,

Peter.

[LanuzaFitbit]

Hello @MrSausages.

Thanks for sharing all of that information and discrepancies with us.

The distance of a GPS tracked activity is not tracked with the stride length given that it is what the GPS if there for. There is a chance that the connection could be lost between your phone and the GPS signal, or your Blaze and your phone, in places and thus the app has to guesstimate based on where you reconnected, that could eat some miles from the total. 

Maybe you could try to record one using only your phone, with MobileRun to test if something changes when you are using your Fitbit. Your phone should be compatible with that feature and it could provide some insight into what is going on.

Let me know if there is anything else that I can help you with.