how fast should you walk a mile
The Speed You Walk. Intensity is also a big factor in determining how many calories you'll burn during any given activity. According to that same Harvard Medical School calorie chart, the 155-pound person will burn 149 calories per 30 minutes walking at a 3.5-mph pace -- or roughly a 17-minute mile. If she speeds up, she'll burn more calories. Walking 1 mile at 4 mph -- which should take her 15 minutes -- she will burn 83.5 calories.