How accurate are the calorie counters on fitness machines? The reason I ask is because I do an hour of elliptical every morning at the gym. The machine I usually use tells me I burn about 500 calories. I used a different machine this morning that had me enter my weight (the one I usually use doesn't ask for weight). The machine I used today said I burned about 750 calories. Same smount of time, about the same resistance, same pace. So which is more accurate? That's a good bit of a difference.