Question about calorie burn on MapMyFitness

bossfan55

I've been using an Armour 39 Monitor with MapMyFitness to keep track of my heart rate and my calorie burn when working out. I just got a Scosche Rhythm + and tried it with MapMyFItness this morning with my P90X Plyometrics workout. MMF showed a 120 average heart rate, but also showed a calorie burn of 915. As much as I wish that was correct, I'm sure that it's not - the same workout using the Armour 39 monitor in recent weeks showed calorie burns between about 560 and 620, which is consistent with various formulas I've used. And, those workouts had the same or similar average heart rates, in the 117-125 range. SO, the new monitor seems like it was measuring the heart rate correctly, but for some reason MMF came up with a much higher calorie burn. I don't think that either sensor calculates calories - I think that's done by MMF, which makes me wonder why the discrepancy. Also, I saw this article on the MMF website which indicates that it doesn't even use heart rate in calculating calories - I wonder if that's an old post that has since been superseded. Does anyone have any insight into this - why the calories burned would be drastically different?

Thanks.