In my experience, these kinda of things are very difficult to calculate as it depends very much on you as an individual -- not just your weight, but you physical makeup, your pace, your incline, etc. etc.
I wouldn't worry about getting an exact number -- you're getting a great workout, so yay for you! I almost never eat back any exercise calories burned, so to me it doesn't really matter what those numbers are.
What TD said. Also keep in mind that the benefit of HIIT is that you CONTINUE to burn calories at a higher rate for several hours after your workout. That's why HIIT is better than steady state cardio for burning calories and raising your metabolism.
I wouldn't worry too much about actual calories burned, but if you REALLY want to know at least what you're burning during the workout, I'd suggest getting a heart rate monitor for the most accurate count.
Last edited by PhotoChick : 12-27-2008 at 02:39 PM.