Any other skiers out there? Calorie burning question

atomicpunk1974

I'm new to this site, and I'm a downhill ski instructor. When I've entered the time I spend out skiing (about four hours actually out on the hills), this site has told me that I've burned 1800 calories. That seemed high to me, so I checked other websites, all of which gave me higher estimates than that. I know that being outside in the cold weather means that my body has to burn more calories just to keep itself warm, but could it really be that many? Or is it possible that this estimate does not include time spent on lift rides? Should I be trying to subtract that out of my four hours? How do other skiers do this?