Swimming burns calories at a rate that varies based on factors such as swim stroke, intensity, and body weight. For a typical 150-pound adult, swimming can burn between approximately 250 and 986 calories per hour. The butterfly stroke burns the most calories, close to 986 per hour, while treading water at a relaxed pace burns the fewest, around 250 calories per hour. Other strokes like freestyle, breaststroke, and backstroke fall in between, with higher intensity swimming burning more calories. For example, freestyle swimming ranges from about 593 to 714 calories burned per hour depending on effort level. Overall, swimming is an effective calorie-burning exercise, and increasing intensity through interval training can boost calorie burn by 25 to 30 percent.
