16.17 - Inaccurate calculation for total ascent and descent

and now, yesterday run with FR955...10m difference on 4,4 km run in the city...start/end point the same

It is barometric so i think when the airpressure changes the Watch measures it. E.g when during the workout a storm is coming up the airpressure drops 

I noticed yesterday. Run on soccer field. So elevation gain should be close to 0.

Yesterday run

The same run with FW14.20, which is correct

yes, this is a commonly known thing, this is how all watches work. But there is a difference when you go for a run with one watch and another, and the old watch will show you the altitude gain/loss the same. Garmins show bad values in almost all measurements on all activities

I'm on 16.17 but I not detect these differences on my activities.

I even switched from Suunto to Garmin because of this problem that MartinRA mentions but on Suunto. After using Suunto for many years I bought a FR955S and after 1 year of simultaneous use I decided to sell the Suunto. Years ago with the Suunto A3P I always had very accurate information, in everything related to altitude, then with the S7 and S9 I started to notice inconsistent information in the altitude recording in the activities. That's why after that year of simultaneous use and comparisons I stayed with the FR955S, besides being lighter, how and being better integrated with the entire ecosystem for my other activities (Virtual Trainer, Cycling computer, etc). Not to mention that each additional feature took years to release when at Garmin I get more updates, more useful and more frequent.

Looks like the problem is still present in FW 17.xx Beta

forums.garmin.com/.../problems-with-altimeter

 I hope they fix it before launching it.
What I don't understand is: there they also mention 15.xx/16.xx and I really didn't have and don't have any problems.

Here is another topic about the same thing: https://forums.garmin.com/sports-fitness/running-multisport/f/forerunner-955-series/334732/altimeter-inaccuracy/1623364#1623364

Unfortunately no changes with the sw version 17.xx for me. I have tried everything. Even contacted with product support but got no answer. Seems like some FR955 watches dont have that issue but others have with the same sw. version. Maybe there's some differences between these watches. For example I have solar version and i bought mine just after launch 02.06.2022. Maybe they had probems with earlier versions of the watches and they changed the hardware later on.

Everyone who has same problems please vote up this BUG report: forums.garmin.com/.../problems-with-altimeter

Of course, here are many more threads with this problem, include mine:

forums.garmin.com/.../altitude-gain-inaccuracies-altimeter-differences-indoor-climbing-bug-on-fr-955

Nobody will fix this... you can fix it by yourself, sell the Forerunner and buy a watch from another brand