Breathing and lung function tests

Tests to measure your breathing

What are they?

Breathing tests measure how well your lungs are working. These tests are used to find the cause of problems such as feeling out of breath. They are sometimes called lung function tests. They measure things like:

  • how much air you can take into your lungs
  • how quickly you can blow air out of your lungs
  • how well your lungs can take up oxygen
  • the strength of your breathing muscles

Your results are compared to what they should be, using predicted values. These values are based on what would be expected in healthy people of your age, height, gender and ethnicity.

Your body mass index or BMI

Your health care professional may also weigh you to calculate your body mass index (BMI) as a way of measuring whether you’re a healthy weight for your height. 

Your BMI is not relevant for predicted values of breathing test results. But it is important because being overweight or underweight can affect your breathing, lung function and general health. Being overweight can cause breathlessness.

Your health care professional will also compare your results with the results of any earlier tests to track your progress.

Tests include:

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Last medically reviewed: January 2017. Due for review: January 2020

This information uses the best available medical evidence and was produced with the support of people living with lung conditions. Find out how we produce our information. If you’d like to see our references get in touch.