Garmin Fenix 6 Pro distance measured much shorter than Vivoactive 4 and Google Maps

Do you have "smart recording" or "every second recording"? It's under device settings. Smart recording takes a reading whenever a large enough change is detected, while every second recording takes a reading every second no matter what. This can have an impact on track accuracy (and heart rate/pace/ect).

A phone GPS is going to be more accurate because it is significantly more powerful - think about how large a phone battery is compared to a watch battery, and how long the charge is supposed to last on a phone compared to a watch. Not sure about the honor band part but I don't trust anything made by Huawei.  Maybe the Chinese device is using Chinese satellites? No idea.

Did you try using GPS/Galileo?

Thank you for your answer.

I have "smart recording". So, I suppose "every second recording" is more accurate, so I'll change to that. I will also try GPS/Gallileo as you suggest. I hope it works, as I just noticed that if you zoom on the map of the Connect App, it shows a route outside of the route that I've been following:

Yes, Huawei and Honor are Chinese, I don't trust them either and I do not use them, but I tested them and, strangely, by default they were more accurate than Fenix 6 with my settings or defaults. Also, strangely again, my previous model, Vivoactive 4 (that is not Pro series as Fenix 6), was more accurate by default than Fenix 6 has been with the settings that I described.

Anyway, thanks again for your answer, I will come back to you in a couple of days when I have tested your suggestions.

Good luck! Hopefully it works for you.

RedSocks157 said:

This can have an impact on track accuracy (and heart rate/pace/ect).

But no effect on distance.

Not true, the polling rate affects where the GPS "pins" that make up the track are recorded. The line is drawn from pin to pin. More pins = more accurate GPS track.

RedSocks157 said:

more accurate GPS track

Read what I said. There is no effect on distance. It is the track display that benefits from the saved points. To clarify, the watch always records at 1 second intervals. What changes when Smart v 1s is selected is the number of data points saved. In Smart recording this is determined by changes in various metrics. Smart recording is really a hangover from the early days when there was limited storage space so smaller activity files were needed. 

But, there is no change to the calculation of the underlying metrics, only what is displayed.

Interesting! Thank you for explaining, I always assumed that the GPS pins were included in that.

Hopefully trying the different satellite settings and such will still help OP get better data!

Unfortunately "every second recording" and GPS/Gallileo brought pretty much the same result. Again the lap was calculated at 270m instead of 330m.  I was running straight on the lines around the field and this is the map that Connect app gave for my activity:

I also tried the last GPS option for running activity, UltraTrac and this is the result for 2 laps again straight on the lines of the field (if you see for the first 50 meters it kept straight, then totally lost it). The map with this setting totally failed, but the lap was calculated a little better, at 300 meters instead of 330m:

I am starting to think that my watch is faulty. Yesterday there was an update that I pushed on the watch but I am not very optimistic that something will change. Is there anything else that you would suggest?

5673910 said:

I am starting to think that my watch is faulty.

Very likely - someone else reported a similar issue 

https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/fenix-6-series/294134/gps-inaccuracy-on-fenix-6s---worst-run-today/1427531#1427531

(plus there is also a long running thread on this)

I have been running a Fenix 6 Sapphire vs. Forerunner 255 and distances are very very very close

https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/fenix-6-series/296268/fenix-6-pro-and-forerunner-255---gps-gains-marginal

I realise that someone else having great results in no consolation to you, but when people get egregiously short or long results then Occum's Razor seems to suggest a device fault to me

Never use Ultratrac though as the results will be like a blind person throwing darts at a dart board- a total miss!

Ultratrac records a point each minute or so, so it's normal.