What is a spirometer?

A spirometer is a device used to determine how well your lungs are working. .


Spirometry is the measurement of lung function with a spirometer. It's one of the simplest, most common lung function tests and may be done for any or all of the following reasons:

  • To monitor lung disease

  • To monitor how well treatment is working

  • To determine the severity of lung disease

  • To help determine whether lung disease is restrictive (decreased volume) or obstructive (disruption of airflow)

After taking a deep breath, a person forcefully breathes into the spirometer as completely and forcefully as possible. The spirometer measures both the amount of air expelled and how quickly the air was expelled from the lungs. The measurements are recorded by the spirometer.

The normal values measured by the spirometer vary from person to person. Your results are compared to the average expected in someone of the same age, height, sex, and race, according to the National Heart, Lung, and Blood Institute (NHLBI). If the value is below 80% of the expected average, it may be a sign of lung disease. If your spirometry results are abnormal, your health care provider may want you to have additional tests.

How often will I need this test?

Your health care provider may want to check your lung function if you have certain symptoms or if you are at risk for lung disease. For example, if you have trouble breathing or a long-term cough. Or, if you smoke. In those cases, spirometry is on an as-needed basis. Many people with lung disease have spirometry regularly. For example, a person with asthma may have spirometry at least every one to two years.