My bmr is too low

[HeidiinTN]

The bmr Fitbit has calculated for me is too low. I am very active so even at rest I am burning more than what their bmr says. I have used Fitbit for months now, and on inactive days I am burning 17-1900, and on active/exercise days, 2000-2400. So why does it use a 1300 cal bmr!? I have never burned that little while wearing it. This is frustrating for one big reason- on days that I charge it for too long, my food log will be inaccurate. Today, I ate 1500 calories and it says I am over since I burned 1300 according to them. So now my food log says I am over target, making it inaccurate and encouraging me to eat less when 1500 is still a 200 calorie deficit based on what I usually burn. 

[JohnnyRow]

I think you have a wrong impression of BMR.  You say on inactive days, you burn 1700-1900 calories, but that is not your BMR.  It would be close to your BMR only if you laid perfectly still in bed all day, eating nothing, not getting up to go to bathroom.

Even on inactive days, you are well abive your BMR if you just get out of bed, walk to the bathroom and refrigerator.

Many people have the idea that you are either at your BMR or exercising, but there is a broad range with much time in between those extremes when you are still burning above your BMR, though not thinking of yourself as working out.  Just sitting or standing up burns more than your BMR.

If you want to get a better idea what Fitbit is using for your BMR, look at your daily calorie burn graph and see what that shows you burning at night when asleep, and multiply that out to 24 hours.

[HeidiinTN]

I see what you are saying. Initially it was using 1300. Now it is using 1440. And yes, that math does add up given I burn 5 cals/min while asleep. I guess my main issue is that Fitbit is using my BMR when my watch is docked, and that is highly inaccurate given I am never going to burn less than 1600 cals unless I am literally comatose. So, on those days where I charge it too long, it under rates me for calories I can consume. I can adjust, but I like looking back on trends and my data, and on those days it will show that I overate even though it should be within zone or green, and that does not help me adjust eating and behavior moving forward. And if I listen to Fitbit and not eat the regular amount, I will be hungry and lose too fast. 

[JohnnyRow]

Re-check your calorie burn while asleep. 5 calories per minute would give you a BMR of 7,200 calories burned per day, just BMR.  My display shows 1.4 cal/minute, and I'm a big guy.  Note the display, at least the one I am looking at, shows calories burned per 15 minute intervals.

Alternatively you could just google BMR calculator.  There are several easily available that give very close results.

But it sounds your main point is Fitbit does not know how many calories you are burning while it is on charger.  That is true.  You could make up some activity to manually log for that time.  But I don't think charging has to be that big an issue.  It doesn't have to be one long charge; some people find just charging while taking a shower will keep the charge nearly steady-state.  Or just charge it a few minutes at a time when you know you are going to be sitting still, say watching TV or sitting at computer, times when you are not going to be burning many calories.  You can buy an extra third-party charger or 2 and a few USB-wall plug adapters from Amazon for reasonable prices so have charger handy wherever you might sit down for a while.