Versa 4 vs Charge 3

[Missfrog57]

I have been using a Charge 2 then a Charge 3 for years. Just got a Versa 4 for my birthday. My calorie expenditure on the Versa 4 is way less that the readings I got from the Charge 2 and 3 for the exact same exercises.  Any idea why?

[LZeeW]

Hello @Missfrog57 and welcome to the Community.  Those three devices have different optical heart rate monitors.  Different monitors perform differently.  In a recent post, a moderator wrote that Fitbit uses different heart rate algorithms in different devices in upgrades.  Keep in mind that these are all estimates.

I also want to point out that your Versa 4 is different from your Charge 2/3 in that the newer Fitbits award active zone minutes, not active minutes.  Active zone minutes are different from active minutes.  A different equation is used.  Active zone minutes are consistent with the current CDC and WHO recommendations for physical activity.  Active minutes are out of date.