Concept2 rowing machine logs many more calories than Charge 6

[Old_Rower]

My Charge 6 consistently underreports the number of calories I expend on a rowing workout than the rowing machine itself.  I'm thinking this may be because the Charge 6 is basing the calories expended on movement and heart rate, without taking into account the resistance level I have set on the machine.  For example, I'm in good shape and set the resistance to the maximum level (10).  The machine records 280 calories expended after 25 minutes, while the Charge 6 shows only 180.  What can I do to correct this?

[Triletics · Accepted solution]

Charge 6 uses only HR to estimate calories while Concept2 has a power meter. I noticed Charge 6 reporting less calories but this is due to different method of estimating energy expenditure (ideally, if you could pair rower to your watch you'd get calories based on power not heart rate like it's done ie. on Garmin). Fitbit has no other way to estimate it. This is also the case for cycling.

[YachatsMike]

I always accept the machine calorie counts over Fitbit calorie counts.  The machines, for the most part, have more information about what you actually did and better algorithms for calculating calories than Fitbit's heart rate / step method.  An example is when I do intervals, I always get smaller values on  my Fitbit for the first interval than I do on the last even though it is precisely the same work.  I always get more Fitbit  calories if I warm up long enough to get in the zone than I do if I start cold.