How do exercise calories factor into the total calories for the day?

[aisuru02]

Sorry if this question has been asked before... I did look around the forums but didn't see anything that was quite addressing my question.

It seems like my Fitbit is primarily figuring out my total calories burned from the day from the number of steps I take... i.e. my daily calorie totals are similar as long as my total number of steps are similar, regardless of the workouts I did.

For example:

On Friday I walked 10,200 steps. My only "exercise" was a 40 minute walk that Fitbit estimates burned around 270 calories. My total calories burned for the day was 2030. 

On Saturday, I walked 10,800 steps. I had an hour long exercise class which burned 428 calories, plus another 40 minute walk that burned 250 calories. Yet the calorie total for Saturday was almost exactly the same as Friday: 2080. Shouldn't it have been higher since I did an extra hour of activity? I guess you could argue that based on steps I was more active in general on Friday, whereas on Saturday I was more sedentary with a few active hours, but the quality of the exercise on Saturday was definitely more high-intensity, so I would expect that I would have burned more calories overall, even with the same amount of "steps."

Thanks!

[JohnnyRow]

First you have a base level of calories from you BMR (basal Metabolic Rate) that are the same every day.

See How does my Fitbit device calculate calories burned? 

On top of that are your calories burned from activity.  These should be based mainly on heart rate rather than steps so I would expect generally that you would have higher calorie burn with the longer time exercising unless, as you suggested, in this case the more sedentary nature of the rest of your day happened to make the numbers come out nearly the same.

That's not much help, but calories are based on intensity, based on heart rate, rather than number of steps.  You could verify this yourself by doing some exercise that gives you very few steps.  Such activities might include pushing a shopping cart or a baby carriage, or walking on treadmill holding hand rail.  Although these do have steps, fitbit often does not recognize them because the wrist is held steady rather than swinging.  With such activities, you should see similar calorie burn without the step count.