Enter the residual volume, expiratory reserve volume, tidal volume, and inspiratory reserve volume into the calculator to determine the total lung capacity.

Total Lung Capacity Formula

The following formula is used to calculate the total lung capacity (TLC). 

TLC = RV + ERV + TV + IRV

Variables:

  • TLC is the total lung capacity
  • RV is the residual volume, the amount of air left in the lungs after a forced exhale
  • ERV is the expiratory reserve volume, the maximum amount of air that can be exhaled from the lungs after a normal exhalation
  • TV is the tidal volume, the amount of air inhaled or exhaled during normal breathing
  • IRV is the inspiratory reserve volume, the maximum amount of air that can be inhaled into the lungs after a normal inhalation

To calculate the total lung capacity, add the residual volume, expiratory reserve volume, tidal volume, and inspiratory reserve volume together.

What is Total Lung Capacity?

Total Lung Capacity (TLC) refers to the maximum amount of air that the lungs can hold. It is the sum of the volume of air in the lungs after a maximum inhalation, which includes the residual volume (air that remains in the lungs after a maximum exhalation), the tidal volume (air that moves in and out of the lungs during normal breathing), and the inspiratory and expiratory reserve volumes (additional air that can be inhaled or exhaled beyond normal breathing). It is typically measured using a device called a spirometer.

How to Calculate Total Lung Capacity?

The following steps outline how to calculate the Total Lung Capacity (TLC) using the given formula:

  1. First, determine the value of the Residual Volume (RV).
  2. Next, determine the value of the Expiratory Reserve Volume (ERV).
  3. Next, determine the value of the Tidal Volume (TV).
  4. Next, determine the value of the Inspiratory Reserve Volume (IRV).
  5. Finally, use the formula TLC = RV + ERV + TV + IRV to calculate the Total Lung Capacity.

Example Problem:

Use the following variables as an example problem to test your knowledge:

Residual Volume (RV) = 1.5 liters

Expiratory Reserve Volume (ERV) = 1.2 liters

Tidal Volume (TV) = 0.5 liters

Inspiratory Reserve Volume (IRV) = 1.8 liters