No logic to calorie calculations

[Fassia]

I do an Aerobic Exercise yesterday and the Fitbit picks it up with the following stats:

1. 39 min
2. 403 calories
3. 128 avg bpm
4. 41% Peak

I do a similar Aerobic Workout today and the Fitbit doesn't pick it up.  I entered the time I started and the duration and got the following stats (Fitbit did not pick this up but gave the stats after):

1. 44 min
2. 205 calories
3. 148 avg bpm
4. 59% Peak

Who came up with the lame calorie algorithm?

Today's workout was obviously a tougher workout but only half the calories.

What a piece of crap.

[Rich_Laue]

Are you upswing the manual mode or letting the tracker decide. 

[Fassia]

Letting the tracker decide but the tracker doesn’t recognize the workout. At that point I enter the start time and duration and the tracker finally notices the workout.