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What Does Spirometry Measure?


Updated March 23, 2009

What Does Spirometry Measure?
Photo © CDC
Question: What Does Spirometry Measure?
Answer: When you inhale and exhale into the mouthpiece of a spirometer, it measures airflow. Spirometers can not only measure how much airflow, but also measure airflow per unit time. Some examples of parameters spirometry can measure include:
  • Forcved Vital Capacity (FVC): The total amount of air that you can breathe out after taking as large a breathe as you can.
  • Forced Expiratory Volume at One Second or FEV1: The amount of air you can forcefully exhale at one second.

Both FVC and FEV1 are important in the diagnosis and treatment of lung problems such as asthma. The spirometer can accurately determine a number of other values and compare them to predicted values in healthy populations.


Clinical Pulmonary Function Testing, Exercise Testing, and Disability Evaluation. In Chest Medicine: Essentials Of Pulmonary And Critical Care Medicine. Editors: Ronald B. George, Richard W. Light, Richard A. Matthay, Michael A. Matthay. May 2005, 5th edition.

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