The total air volume of the lungs is about 4 to 6 liters and varies with a person’s size, age, gender, and respiratory health. Normal shallow breathing only moves a small fraction of the lungs’ total volume into and out of the body with each breath. This volume of air, known as tidal volume, usually measures only
around 0.5 liters. Deep breathing can force more air into and out of the lungs than during shallow breathing. The volume of air exchanged during deep breathing is known as vital capacity and ranges between 3 to 5 liters, depending on the lung capacity of the individual. There is a residual volume of around 1 liter of air that remains in the lungs at all times, even during a deep exhalation.