What is the capacity of the lungs when they are fully inflated?

The total lung capacity refers to the maximum volume of air the lungs can hold when fully inflated. This includes all components of lung volume: the tidal volume (the amount of air breathed in and out during normal respiration), inspiratory reserve volume (the additional amount of air that can be inhaled after a normal inhalation), expiratory reserve volume (the additional amount of air that can be exhaled after a normal exhalation), and the residual volume (the amount of air remaining in the lungs after a forceful exhalation).

In contrast, vital capacity represents the maximum volume of air that can be exhaled after a maximum inhalation, which does not include the residual volume. Residual volume itself is the volume of air that remains in the lungs after a full exhalation and is thus not a measure of total lung function when fully inflated. Inspiratory reserve volume is a subset of lung volumes that applies specifically to additional inhaled air, but does not encompass all lung capacity. Therefore, total lung capacity is the most comprehensive measure for understanding the full inflation capability of the lungs.