- Move the marker to the bottom of the numbered scale.
- Stand up straight.
- Take a deep breath. Fill your lungs all the way.
- Hold your breath while you place the mouthpiece in your mouth, between your teeth. Close your lips around it. Do not put your tongue inside the hole.
- Blow out as hard and fast as you can in a single blow. Your first burst of air is the most important, so blowing for a longer time will not affect your result.
- Write down the number you get. If you coughed or did not do the steps right, do not write down the number. Do it over again.
- Move the marker back to the bottom and repeat these steps 2 more times. The highest of the 3 numbers is your peak flow number. Write it down in your results log.
Update Date 4/26/2010
Updated by: Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.