The calories burned on Qalorie differ to the calories burned on an exercise machine/fitness tracker/watch. Why is this?

Our calculation, while accurate, is less accurate than a fitness tracker that can consider more info. Fitness trackers can monitor your heart rate and many other variables to give much more precise caloric burn prediction. However, our estimation is still accurate and will not vary considerably. Nonetheless, remember that even fitness trackers are not 100% accurate.