How accurate are the calories burned counters on exercise equipment?

The calorie counts provided by exercise equipment are only estimates using weight, age and pace and do not take into account body types or exercise form. These machines can overestimate calories burned by up to 20 percent.

Many manufacturers admit the calorie counts provided by exercise machines are only rough estimates using body dimensions. These estimates may improve in accuracy as exercise technology improves, however. Heart rate and distance measurements provided by these machines have been found to be accurate. More calories are burned when exercising outdoors rather than on a treadmill, as the treadmill keeps the body stationary and thus doesn't require as much work on the runner's part.