Mine is off, but only by 3 calories. MFP says 608 (it's afternoon here) and Fitbit says 611. By my own calculations, Fitbit is right. (I keep a spreadsheet and mine presently says 611.5 calories eaten.)

Me neither. I only log on my spreadsheet and MyFitnessPal. So FitBit gets it from MFP. So I don't know why it's any different at all, unless it's getting the separate foods from MFP and putting its own calories on them.

My guess is that Fitbit calculates calories from the carb, protein and fat numbers that MFP sends, rather than taking the calories from MFP info directly. This could result in rounding differences between the two programs. Being off by 30 calories seems high for that, though, so - if you care about what Fitbit is saying regarding calories - then compare the calories for each meal. Occasionally, I get two entries in Fitbit for the same meal (when I've edited the meal in MFP) and I just delete the one that is wrong.

Mostly, though, I do what editorgrrl says - I go by MFP's calorie goal and only casually look at what Fitbit indicates.

editorgrrl wrote: »

Ignore your Fitbit calorie goal and follow MFP's, eating back your adjustments.

^^^^^ This. Fitbit food database is not as good as MFP's either, so just use MFP for your food tracking.