There and back walk shows completely incorrect elevation profile

[SidewaysSyd]

I've just completed a short walk to a friend's manure pile, pushing a wheelbarrow. I did the same walk two days ago. Looking at the Dashboard record of both walks, the elevation profiles are quite different. More than that, you'd expect the individual profile to be symmetrical but they're not. Both elevation profiles show a continual drop. Even though I left home and arrived back home, one elevation shows I arrived home and am 24 feet lower than when I set off and today, I'm 31 feet lower than when I set off!

How can this be?! Is it because my arms weren't moving while pushing the wheelbarrow? 

[EdsonFitbit]

Thank you for visiting the Fitbit Community @SidewaysSyd.

Thanks for the information provided.

If you're doing something like pushing a stroller or shopping cart, your Fitbit device will count your steps and movements but we cannot guarantee accurate readings.

See you around.

[SidewaysSyd]

Thanks for the clarification

[t.parker]

@SidewaysSyd it doesn't matter for elevation whether you are moving your arms. @EdsonFitbit didn't seem to understand the question, hence an unrelated response.

From my experience with Fitbit, I could notice that the elevation uses barometric pressure and it is not corrected by the data coming from the GPS. The result is that if a) there are sudden weather changes b) you obstruct somehow barometer, c) or anything else happening with the sensor, then the elevation may go wrong. Fitbit seems to be using relative elevation which I can usually see in my runs and bike rides. The reference elevation is based only on the current atmospheric pressure (no calibration using GPS data).

Here's an example:

The starting point real elevation is 16m. Garmin Fenix 6 Pro (pink) adjusted it to 17m (good enough), but Fitbit Sense starts with 10m. Now, if it goes with relative elevation using the barometer then obviously, starting with the wrong reference altitude, the error will affect readings until the end. Also, interesting thing is that if you look at the first spike Fitbit goes always up and down, the elevation is more "jagged". This only confirms that the GPS data isn't contributing. It may get a lot worse when you cycling because you're moving a lot faster, it may be windier, etc. So here's another example, one of my bike rides:

It is crystal clear which elevation is correct. Garmin (blue) matches actual elevation better because it uses DEM (Digital Elevation Model) data to correct the altitude and take care of the drifts caused by the incorrect barometer readings. This is also the reason, why the reference altitude at the start is correct - it's auto-calibrated. Otherwise, I would see a similar jagged line as for Fitbit. Fitbit doesn't do autocalibration and uses barometric data as it is so with sudden air pressure changes you may in fact observe the different elevation in the same point.

On Fitbit, it isn't a bug. It's just the simplest implementation of the elevation capture. You may request improvement of that feature in the Feature Suggestions forum but at this moment this is how it works and there is no workaround 🙂