Are these even close to accurate?

Mine is fairly accurate sometimes but I don't rely on it. I know roughly the burns of most things I do so when I see FitBit doing something wonky, I just delete the workout and input the workout manually, including the calories.

Mine gets wonky sometimes mostly due to the HRM doing something weird. Like yesterday I did a 45 minute interval ride on my bike trainer...in the working sessions, my HR was 155 per my Garmin bike computer and HRM chest strap...but my FitBit was giving me a HR of 88. FitBit in this case ended up underestimating my calorie expenditure.

On Monday evening we went out as a family to walk the dog and we go about 1 mile. At one point FitBit was giving me a HR of 150 and there's no way that's possible with a little family dog walk at about 3 MPH on a flat surface...it gave me over 200 calories for a mile long walk...I just deleted it.

All in all, I've found my FitBit to be relatively accurate in total calories per day...it appears to be on average inflated by 150-200 calories per day as compared to my own data. So if it tells me I burned 3200 calories in a day, I presume it was closer to 3,000...if it gives me 3,000 I presume it's closer to 2,800 for the day, etc.

Also, if you're doing a lot of anaerobic work where your HR gets really high in short bursts and then comes back down, your FitBit and any other HRM will inflate energy expenditure from that workout. Mine is usually fairly commensurate with what I know for cycling, but as exampled above, sometimes it can be wonky. Weight lifting is pretty much hit or miss. Sometimes it will give me something comparable to what my own data indicates which is about 130-150 calories per 30 minutes...and then sometimes it'll give me like 300 calories for a 30 minutes lifting session which I know is absurdly high.

newshell_mom wrote: »

It was a boxing/cardio class

Not even remotely close. Probably the lowest estimate is optimistic

My fitbit has been very reliable except for the first month when I had to play around with the stride lengths for running and walking.

Something in your settings is wrong if it is giving you a burn that high.

newshell_mom wrote: »

The class had HIIT style burst as well

HRMs are very bad at estimating calories for this kind of activity. HRMs generally do a reasonable job of estimating calories expended for steady state aerobic cardio.

sarahthes wrote: »

It's usually close for running or walking. Anything else is a crapshoot.

This exactly. Your FitBit is meant to measure steps. Boxing is way outside of what it can accurately measure.