Walking is great exercise, and a perfect way to begin an exercise routine if you're just starting out. For those days when you can't (or don't want to) walk outside, take your walks indoors, on a treadmill. Walking on a treadmill can help you burn calories if you're trying to lose weight and help you stay in shape when you are trying to maintain your health and fitness routine. If you're worried that treadmill workouts can be boring, learn how to mix up your workout here. How many calories you burn on a treadmill depends on your speed, weight and gender. To see how many calories you burn on a treadmill at 4 mph, use the calculator below.