Before I begin -- let me say that I know that the "calorie" total on gym machines aren't usually accurate. I'm just shocked at the discrepancy, and I'm wondering if it's not me doing something wrong.
So today was one of my "hard cardio" workout days. I typically do 60 minutes HIIT on the elliptical machine; today was no exception. Normally after 60 minutes HIIT the machine says I burn something like 650 cals, +/- 5%
Let me say also that I normally push my heart rate to 170-172ish during the hard intervals of the HIIT; I do 1 minute high-intensity (heart rate 172ish), one minute low-intensity (heart rate 156-ish). I was a bit annoyed at my HRM because it believes that for my age and height (see signature) that 170 is WAY TOO HIGH and OUT OF THE ZONE (actually, it thinks 156 is "out of the zone" too, and it was beeping at me like every 20 seconds, though I ignored it), but I feel fine pushing that high with my heart rate. When I hit 180, I usually get a little woozy, so I don't push it there.
I wore the HRM both to and from my 5-minute walk to the gym, so I was expecting maybe another 50 cals or so on my total, to make it maybe 700-ish when I got home.
Imagine my surprise when I looked down at my wrist and the HRM proclaimed that I had burned 1,201 calories in one hour and twenty minutes (ten minutes of stretching is in there somewhere).
Personally, I would LOVE to believe that I blast through 1200 cals on my cardio days (including my little walks), but a very large part of me is skeptical. Is the machine THAT far off? Or am I just THAT much of a beast?

Or perhaps my HRM is set wrong, though I set it myself not three days ago and entered my weight and height as accurately as I could.
I'm just wondering if anyone else has had such vastly different things said by machines vs. HRM, or if anyone can tell me whether or not, given my type of cardio, 1200 cals seems at all feasible? I'm happy to give more details. I do consider my workout to be very hard - I'm breathing hard through it, my face is lobster-esque when I'm done, and my whole body is nice and sore (though not painful) and I keep that heart rate up. Again, though, it's not like I'm making myself sick -- just pushing.
Thanks very much!
~Terri
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Terri
Female, 28 years old, 5'4 1/2" tall
Starting weight 1/4/11 = 215.2 lbs.

Weight 9/3/12 = 164.9 (net: -50.3 lbs.)
Current mini-goal: 160 lbs.
Next mini-goal: 150.2 lbs.
<--- Official "Healthy BMI" weight 
Estimated final goal: 130 lbs.
"You don't have to change your life today. You only need to change your day today."