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How to Measure Your Peak Expiratory Flow

Set meter to lowest number: Step 1

Picture of setting the peak flow meter at its lowest number

Put the pointer on the gauge of the peak flow meter to 0 or the lowest number on the meter. In the photograph, this is about 50.

Attach mouthpiece: Step 2

Picture of attaching mouthpiece to peak flow meter

Attach the mouthpiece to the peak flow meter. Some meters don't have a separate mouthpiece.

Take a deep breath: Step 3

Picture of inhaling to get ready to use the peak flow meter

While standing, take a deep breath.

Put mouthpiece in your mouth: Step 4

Picture of putting peak flow meter mouthpiece in the mouth

Put the peak flow meter mouthpiece in your mouth, and close your lips tightly around the outside of the mouthpiece. Don't put your tongue inside the mouthpiece.

Breath out hard: Step 5

Picture of exhaling into the peak flow meter

Breathe out as hard and as fast as you can for 1 or 2 seconds. A hard and fast breath usually produces a "huff" sound.

Check your number: Step 6

Picture of a peak expiratory flow result of about 180

Check the number on the gauge, and write it down. This is your peak expiratory flow (PEF). In the photograph above, the PEF is about 180.

ByHealthwise Staff
Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine
Specialist Medical ReviewerLora J. Stewart
Last RevisedMarch 17, 2011

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