You hop off the treadmill, look at the screen, and WOOHOO you burned 600 calories!!
You're probably feeling a little skeptical of this number and rightly so! Several studies conducted on the topic of calorie estimation have turned up some concerning results. But the general theme is that calorie estimation during exercise is just that...AN ESTIMATION. A good rule of thumb is to always assume that the calorie counts given by a cardio machine or app is generally overestimating how much you actually burned. To what degree they're overestimating, we're not 100% sure.
Here are some practical strategies to help you get the most accurate calorie counts.
Use cardio machines that ask for lots of information before you start such as: age, weight, fitness level, body fat, etc.
Enter every bit of information the machine asks for. More information means more accurate calorie counts.
Keep track of your breathing and pulse rate. This will let you know if you actually worked as hard as the machine thought you did.
If you felt the exercise session was easy, then you'll need to purposefully underestimate your calorie burn.
Use correct form (no leaning or holding onto handles); this will ensure a more accurate count.
A University of California at San Francisco Study gave these overestimate percentages for each type of cardio machine.
Treadmill: Overestimated by 13 percent.
Stationary Bike: Overestimated by 7 percent.
Stair Climber: Overestimated by 12 percent.
Elliptical: overestimated by 42 percent.