I use my Garmin watch just for exercise tracking and use the Fitbit platform for daily step tracking. The calories burned when I track exercise with my Garmin watch is always more than my Fitbit. I used to have an inspire 2 (fairly basic watch) and the max/avg HR was often fairly different from my Garmin so I figured it just wasn't as good at tracking exercise, however I got a Pixel Watch 2 for Christmas and still have the big calorie discrepancies even when the HR values are much closer. I'm now wondering if maybe one platform is total calories and the other is differential (above my baseline). Anyone know which Garmin tracks?
