Garmin Watches irregularities

[Thisonepotato]

Just been for a run with my son, I wear a Garmin Forerunner 745 and he was wearing his Forerunner 45. My total elevation gain was 33m his was 21m, 21m is spot on for this route.

Big difference for the same run though.

What's going on with my watch?

[gregs656]

Nothing, they're just not perfect.

[downthepub]

I have a FR 945 and my wife a Venu 2 - very often our dog walks & parkruns will show up differently. Seems par for the course.

[essayer]

Is one barometric and the other not? GPS elevation isn’t as accurate

[anonymous-user]

The 45 uses GPS to work out altitude. There are challenges with this due to the way GPS works. The 745 has an altimeter and barometer in it, this is a much more accurate way of working out elevation. Are you sure it’s the 45 that’s correct not the 745? How do you know the elevation for the route is 21?

[Derek Smith]

Thisonepotato said:

Just been for a run with my son, I wear a Garmin Forerunner 745 and he was wearing his Forerunner 45. My total elevation gain was 33m his was 21m, 21m is spot on for this route.

Big difference for the same run though.

What's going on with my watch?

How tall are you?

[anonymous-user]

Derek Smith said:

Thisonepotato said:

Just been for a run with my son, I wear a Garmin Forerunner 745 and he was wearing his Forerunner 45. My total elevation gain was 33m his was 21m, 21m is spot on for this route.

Big difference for the same run though.

What's going on with my watch?

How tall are you?

12 meters taller than his son you've solved it!

[anonymous-user]

CheesecakeRunner said:

sebdangerfield said:

The 45 uses GPS to work out altitude. There are challenges with this due to the way GPS works. The 745 has an altimeter and barometer in it, this is a much more accurate way of working out elevation. Are you sure it’s the 45 that’s correct not the 745? How do you know the elevation for the route is 21?

Mostly it’s this, but there are circumstances where the barometric altimeter isn’t as accurate, and this is why Garmin provide the “elevation corrections” feature. This uses map data and your recorded route to work out the elevation gain/loss rather than GPS or the altimeters.

https://support.garmin.com/en-GB/?faq=R4I5hFfk8g...

Of course, I'd forgotten about that, I don't think my old 910 has it. A really neat solution to the inaccuracy.

[mathmos]

I have a regular morning walk I do, about 3 miles....same route every time. My elevation gain can vary as much as 20-30m on the same walk, assume it's something to do with atmospheric pressure

[Thisonepotato]

Thanks all. I am 5ft 7 on a good day son is 4ft. I presumed his watch was correct as I used Stravas correct elevation on my run and it changed elevation to the figure that matched his.

It was also a windy high pressure day which I believe can cause issues with barometers.