Here are the basic steps for using a peak flow meter:
Set the sliding indicator on your peak flow meter to the base of the meter.
Stand up straight and remove any gum or candy from your mouth.
Take a deep breath to fully inflate your lungs.
Put the mouthpiece of the peak flow meter into your mouth and close your lips tightly around it.
As forcefully as possible, blow out as quickly as you can. The force of your breath moves the indicator along the numbered shaft of the peak flow meter. The number opposite the indicator represents the PEFR.
Repeat these steps two more times and write down the highest number that you reach. Be sure to take the measurement three times whenever you use the peak flow meter.