**Figure 1.01.** Standard (static) lung volumes as measured with a spirometer.

**Tidal Volume (TV)** is the volume of air moved in and out of the respiratory tract (breathed) during each ventilatory cycle.

**Inspiratory Reserve Volume (IRV)** is the additional volume of air that can be forcibly inhaled following a normal inspiration. It can be accessed simply by inspiring maximally, to the __Maximal Inspiratory Level__.

**Expiratory Reserve Volume (ERV)** is the additional volume of air that can be forcibly exhaled following a normal expiration. It can be accessed simply by expiring maximally to the __Maximal Expiratory Level__.

**Vital Capacity (VC)** is the maximal volume of air that can be forcibly exhaled after a __Maximal Inspiration__. VC = TV + IRV + ERV.

**Residual Volume (RV)** is that volume of air remaining in the lungs after a __Maximal Expiration__. It cannot be expired no matter how vigorous or long the effort. RV = FRC - ERV.

**Functional Residual Capacity (FRC)** is the volume of air remaining in the lungs at the end of a normal expiration. FRC = RV + ERV.

**Total Lung Capacity (TLC)** is the volume of air in the lungs at the end of a __Maximal Inspiration__. TLC = FRC + TV + IRV = VC + RV

**Minute Volume** is the volume of air exhaled per minute.

**Maximal Breathing Capacity** (also called "Maximal Voluntary Ventilation") is the maximum volume of air that can be exhaled by voluntary effort in a 15 second interval. This volume is multiplied by 4 and expressed as liters per minute.

Another graphical representation of Lung Volumes.