How does Fitbit estimate calories burned?

[irenek1990]

i switched from fitbit charge 2 to apple watch and i wanted to know if the results are similar. fitbit autorecognizes exercise, whereas on apple watch you have to put it manually. but i find that my fitbits calories burned are less than my apple watch, does apple watch overestimate them?

Moderator Edit: Clarified Subject.

[MarcoGFitbit]

Hello @irenek1990, have a warm welcome to the Fitbit Community, it's great to have you on board. 

Thanks for bringing this to my attention. Please note that if you're wearing a tracker with heart rate included, Fitbit will estimate your calories based on your heart rate and your basal metabolic rate (BMR) is the rate at which you burn calories at rest just to maintain vital body functions like breathing, heartbeat, and brain activity. Your BMR usually accounts for at least half of the calories you burn in a day and is estimated based on the physical data you entered when you set up your account: gender, age, height, and weight.

The calorie burn estimate that Fitbit provides takes into account your BMR, the activities recorded by your tracker, your heart rate and any activities you log manually.

I hope this resolves your inquiry, if there's anything else I can do for you, please feel free to reply.