The additional volume of air a person can expire by forcible expiration is called Expiratory Reserve Volume (ERV). Average ERV is 1000 mL to 1100 mL. Inspiratory Capacity (IC) is the total volume of air a person inspires post a normal expiration. Inspiratory capacity includes tidal volume and inspiratory reserve volume (TV+IRV). The total volume of air expired after a normal inspiration is Expiratory Capacity (EC). Tidal volume and expiratory reserve volume (TV+ERV) are both included in EC. Functional Residual Capacity (FRC) is the volume of air remaining in the lungs after normal expiration. Includes both ERV+RV.