Exercise/active zone minutes

[StephSS]

There have been a few times I have forgotten to select/start “weights” as an exercise on my watch, so I manually enter it in the app later. But when I forget I only get around 1-3 active zone minute for that period, when do pretty much the same workout and select “weights” on my watch I get 50 or more. Shouldn’t that number be around the same since it’s based on my heart rate? 
edit (more info) Before I logged it manually the watch was still just showing 1 zone minute after the workout. Why would it read such different data when in exercise mode? 

[JohnnyRow]

Yes, zone minutes, and also calories burned are based on heart rate, but when you manually log the workout after the fact, whatever parameters you enter for the workout override whatever data was actually recorded, including heart rate.  It is as if Fitbit figures if you are manually logging it afterward, it must be because you were not wearing the watch, so it just goes by whatever you enter as parameters and guesses what your heart rate must have been from that, and assumes it was a steady heart rate the whole time.  You should be able to test that by changing the parameters and see the calories burned, and I suppose zone minutes, change, though I have never bothered messing with that.

I understand you sometimes forget to start the Exercise App, but, in my mind, that is a big downside for people who always manually log their workouts and never use the Exercise App.  I wish Fitbit somehow made this information more obvious to everyone.

[StephSS]

Before I logged it manually the watch was still just showing 1 zone minute after the workout.

[JohnnyRow]

Well then, ignore my elaborate well thought out answer.