Venu 4 – inconsistent elevation gain on the same cycling route

I am assuming that this is similar even though I walk and I just check out my floors climbed stats.

One day I'll walk to work and back home in the evening and it'll show ten floors. Another day I'll do the same and at the end of the day it'll show 2.

This puzzled me and my Google foo tells me I must make sure the hole for the barometer isn't blocked. So I wash it out and the next day the watch shows ten floors. but the day after, back to the problematic reading. 

I take these readings with a grain of salt but they do tend to vary a lot. I'm wondering if something is up with the firmware at times

Unfortunately, I couldnt help you but I have exactly the same problem on my Venu 4:
- Took the exact same ride on 2 consecutive days - one time it showed 1519m, another day 1041m... (true value should be around 1100m)
- GPS setting was the same -> auto select; other readings such as my route, the distance, ... showed identical values. 
- The visualized starting elevation and highest elevation are basically the same (deviation <5m).
- The elevation plots look roughly same but when you look more exactly the reading on the second run (1041m) look smoother and less detailed or in other words the first run (1519m) might track height differences when there are none (maybe jumping sensor readings which dont get cancelled out by the algo). 

Furthermore, on my running track (basically a flat round trip with starting point = end point) it always shows about 4-6 m less up than down movement (e.g. 23m up, 28m down). 

In my opinion such inaccurate altitude recordings are inacceptable since we pay a premium price and my previous 10y old watch for less money provided better results...

Thanks for the response. However, I don't think the troubleshooting steps address the main issue described here.

In my case, the starting and ending elevation are essentially identical (~75 m), and the maximum elevation is also practically the same (~410 m). The GPS track and the overall elevation profiles are also very similar.

The problem is therefore not simply an incorrect absolute elevation or calibration. The issue is the calculation of cumulative elevation gain: on essentially the same route, the watch recorded 601 m on one ride and 835 m on another.

This makes me wonder whether the issue is related to elevation filtering/smoothing or the algorithm used to calculate cumulative elevation gain, rather than simply the calibration or obstruction of the barometric sensor.

Could Garmin please clarify whether there are any known issues with elevation-gain calculation on the Venu 4, or whether this behavior is being investigated as a possible firmware/software issue?

I am happy to provide the activity data if that would help with investigating the issue.

I followed your recommendation and changed the elevation source of the activity in Garmin Connect from the elevation data recorded by the Venu 4 to Garmin DEM.

The result showed a very significant difference:

Original Venu 4 elevation data: 835 m
Garmin DEM: 578 m

This is the exact same recorded activity and GPS track. Furthermore, another recording of essentially the same cycling route resulted in 601 m elevation gain, which is consistent with the Garmin DEM result of 578 m and with the expected elevation gain of approximately 550–600 m for this route.

This makes the difference particularly significant. The Venu 4 sometimes appears to record or calculate substantially more elevation gain than the actual route would indicate, despite the starting elevation (~75 m), highest point (~410 m) and ending elevation (~75 m) being practically identical.

I understand that Garmin DEM can be used to correct an individual activity, but this is not really a satisfactory solution for me.

I purchased the Venu 4 specifically because I expected accurate sports tracking, including elevation data. I would like the watch to record accurate elevation gain directly, without having to manually change the elevation source after every ride.

Could you please confirm whether this behavior is considered normal for the Venu 4? If not, I would like to know whether this could indicate a hardware or firmware issue, particularly with the barometric elevation data or its filtering/calculation, and whether Garmin is investigating this behavior.

Thank you.

Exactly same for me:
- followed recommendations (change single activity to DEM) and suddenly 1519m -> 1059m (seems like correct value). 
- my starting elevation, highest point, ending are also practically identical
- same use-case; Garmin DEM solution for single activity is not satisfactory
- I am also interested in those questions - please answer

Furthermore: 
Below the article "https://www.dcrainmaker.com/2025/09/garmin-venu-4-hands-on-everything.html" I found a comment from "ekutter" (Reply #121 and #123) who talks about the driving airstream depending on the wrist position on the bike might be the reason for the deviations (would indicate a design flaw). 

fwiw, every Garmin watch I've ever had has been inconsistent with Elevation from day to day, on the exact same course.   I have a Venu 4 and a fenix 8 currently; 3 days ago the fenix 8 recorded double my usual elevation for the same course I do 5 days/week.  It is what it is.   You can edit the activity after the fact (on the web only, I think?) to choose how it calculates elevation.  That'll fix it for the activity, but like in my case, it didn't take away my "credit" for climbing double my usual vertical gain, making my activity seem more strenuous than it actually was. 

 Garmin - DK  It has now been over a month without any response. This issue cannot simply be ignored. Please provide an official response and clarify whether Garmin intends to investigate and resolve this problem. Otherwise, affected customers may have to consider further action.