Quote Originally Posted by Eden
Does the elliptical machine ask for your weight? - if it does not it may be giving you an estimate of the calories burned by a typical 160 lb man....

Just remember anyway you do it, unless you are willing to undergo and pay for some pretty extensive testing all you'll ever get is an estimate. I think some of the women here may know some sources of calorie counters they consider to be more accurate than others.
Thank everyone! Yep, the machine asks for your weight. Obviously, the idea of burning 300 calories is so much more appealing that 197 (heck that's an extra glass of wine!).