The calories consumed for an indoor activity is upto 2 to 4 times that of the outdoor activity of the same nature given the same conditions.
For instance, the active calories consumed for an outdoor walk for 25 minutes covering 1.5 km is shown as 50 (avg. heart rate 114 bpm). I walked the same course the next day but with the indoor workout. The indoor workout under the same conditions is shown to burn 150! This also applies with a treadmill.
It gets a little annoying when a no-sweat treadmill session can burn 100 calories while a tiresome outdoor brisk walk burns less than half that amount.
The same also applies to cycling. 10 minute outdoor cycling covering 2.35 km (155 bpm) results in 35 active calories burnt. The same with indoor cycling shows 120!
I've been noticing this difference for over 2 months now.
What's wrong with the whole calorie consumption system in the Apple Watch? Which one is (more or less) accurate? Indoor or outdoor activity?
Update: problem persists with WatchOS 5.0.1