How to Measure Vital Capacity

Vital capacity (VC) refers to the volume of air exhaled maximally after a maximal inhalation. It is the most intuitive and objective indicator for assessing pulmonary function.

VC can be measured using a spirometer. The specific procedure is as follows:

1. The patient stands upright and performs one or two deep breaths.

2. Holding the spirometer’s handle with both hands, the patient slightly tilts the head backward, inhales deeply to maximum capacity, then places the mouth tightly over the spirometer’s mouthpiece and exhales completely until no further air can be expelled.

3. The value displayed on the screen represents the vital capacity.

Typically, VC is measured twice during testing. In healthy adults, average VC is approximately 4,300 mL in males and 2,800 mL in females. If VC is low, exercises such as chest expansion and arm swinging may help improve it; aerobic activities—including jogging, swimming, soccer, and basketball—can also enhance lung capacity.