Over the years I've found Garmin devices only show about half the number of calories of other devices including Polar, Wahoo, Cyclemeter, etc. Someone is wrong as I've used multiple brands on the same exercises being fed from the same heart strap and power meters and the calories is always dramatically different.
I've asked the question of Garmin on occasion but have never received a good answer.
For example, I did a short run with one of my grandson's on Saturday where Garmin said 222 calories and Cyclemeter said 564 calories where both were being fed by a Wahoo heart strap. Further more at 90 pounds and 54 years difference is age my calories on my Fenix 6X were essentially the same as my grandson's on his Fenix 5X which I doubt is accurate at all. By simple physics it take a lot more energy to move a load 78% heavier.
In another example yesterday, I cycled for 24 miles where Garmin Edge 1030 reported 627 calories and other device reported 1457 calories with both being fed by Stages power meting and Wahoo heart strap.
Since most everything I've used for the last 15 years tends to agree with the higher number, I'm starting to think Garmin's calorie number are just garbage! Any thoughts?
Making matters worse, my Fenix 6X was reporting a heart rate of about 65 while my real heart rate was above 120 on both the Edge 1030 and Cyclemeter.
