Biking/General calorie question

[Bik3rjon]

Hiya,

Can you tell me how my Fitbit calculates my calories burned during exercise, all my searches just talk about BMR, not the extra calories during exercise. For instance I like to go mountain biking. I use the connected GPS in the "Bike" activity. My Fitbit now knows my speed, where I've gone, my climbs/falls, HR etc. Now, I imagine if I was to use the "Bike" activity and go road cycling then my average speed would increase dramatically, much lower rolling resistance etc, but average calories burnt over the same amount of time would be similar or maybe even less. Would it know this from my heart rate as it doesn't know when I'm mountain biking or road riding as they are not different activities? If so, as we all accept that a wrist based HRM is not actually massively accurate, not due to Fitbit but just the current tech, then how accurate are the calories burned during an exercise like this? When I go to the gym I do notice the machines and my Fitbit give a very similar calorie burnt count +/- 10-15% normally, but when I go mountain biking my activity syncs with Strava and I get wildly different results. For instance on my last mountain biking activity I got 2149 calories on Fitbit, but 560 calories on Strava. How come there's such a large variation? I imagine that the Fitbit result was probably a lot closer, but would be keen to understand what's going on there. 

Cheers!

Jon

[FerdinandFitbit]

Hi there @Bik3rjon. Welcome to the Fitbit Community Forums, I'm happy to see you around! 🙂

When it comes to calories burning, if you own a tracker that uses a heart rate monitor as in your case with the Blaze, the heart rate monitor will help determine the calories you burn during the day in any type of exercise. Now, this will be different for everyone and also, due to different technologies, results might be a little different to the ones you would get from a chest strap or other machines. Regardless of what type of activity you're doing, the heart rate monitor will be able to detect your blood flow and depending on the effort you're putting on each activity throught the day, it will calculate the calories you burn.

Hope this makes sense. Let me know if you need more help with this!