HRM, Apps and calories burned

MKknits

I just got a Polar FT7 and I really like it, I'm a numbers nerd so it is motivating to me to have all of that data. But I'm curious about the differences I'm seeing in my calorie burn between two apps. I use Polar Beat while working out to see the graph and what zones I am in, plus I like the voice cues it gives. But I also run mapmyfitness (now because we are stuck still doing gym workouts with all of this snow) because it is easier to tie that to MFP.

Today I did a half hour on the elliptical at decent pace. I'm 5'8" and 284lbs my average heart rate was 148, Polar Beat told me that I burned 300 calories, and mapmyfitness told me I burned over 900. That is a huge difference which app is correct? They are both set to my height and my weight. They are both getting the information from my HRM. Usually I don't eat back my calories unless I go over 300 calories used for exercise so generally I haven't worried about the difference but today I'm stumped.

marcyj

Polar Beat's output sounds a lot more reasonable, though perhaps a tad on the low side for the weight and avg bpm. Mapmyfitness seems really high since your heart rate wasn't through the roof. I use the digifit app right now to tie in with mfp, and it seems to be pretty accurate.

MKknits

I'll go look into digifit I just like mapmyfitness because it ties into so other mapmy... apps (mapmyhike and so on) and a lot of my friends are on it.