Normal lung capacity is between 4 and 6 liters, and the average human total lung capacity is approximately 5.8 liters, according to The Physics Factbook. Lung capacity varies widely depending on a person’s age, sex, weight and activity level.
Females have a 20 to 25 percent lower total lung capacity than males on average, and people who smoke also have much lower lung capacities, states The Physics Factbook. While the total lung capacity is the maximum amount of air that the lungs can hold, the average person only exchanges approximately 0.5 liter of air with each breath, known as tidal volume. Total lung capacity is the combination of vital capacity and residual volume. Vital capacity is the maximum volume of air that a person can inspire after forcefully and maximally exhaling, while residual volume is the volume of air remaining in the lungs after such a forceful exhalation.