The number of calories burned while walking a mile varies with the intensity of the exercise and the weight of the individual. Individuals burn roughly the same number of calories whether they walk at a slow or a moderate speed, although greater differences show up once speeds reach 4.5 mph.
An individual who weighs 120 pounds burns 68 calories per mile when walking at 2 mph, and that same individual burns 87 calories when the speed increases to 5 mph. The heavier a person is, the more calories the individual burns when exercising. A 200-pound person who walks at 2 mph burns 114 calories per mile, and that same individual burns 145 calories when walking at a speed of 5 mph.