Discharge Instructions: Using a Peak Flow Meter

A peak flow meter measures how fast you can push air out of your lungs. Your peak flow reading may be an early sign that your asthma is getting out of control. Steps for using a peak flow meter are below.

I need to measure my peak flow:

  • ___ time(s) a day

Check all that apply:

  • ______ When I wake up

  • ______ At breakfast

  • ______ At lunchtime

  • ______ In the afternoon

  • ______ At dinnertime

  • ______ In the evening

  • ______ At bedtime

  • ______ As needed, when I feel short of breath, chest tightness, or have wheezing

For example, your provider may want you to measure your peak flow two times every day, when you wake up and before you go to sleep.


Hand holding peak flow meter, setting marker to lowest point.

Woman blowing air into peak flow meter.

Hand holding peak flow meter.

Hand writing in peak flow log.

Set marker.

Blow into mouthpiece.

Check marker.

Write down marker number.

Checking peak flow

 Bring your peak flow meter and your record of daily peak flow readings to your office visits. Ask your provider or nurse to check how you use your peak flow meter to be sure you are doing it right. Follow these steps to take your peak flow reading:

Step 1

  • Move the marker to 0 or to the lowest number on the scale.

  • Stand up. If you can't stand, sit up straight in a chair. Be sure you're in the same position each time.

Step 2

  • Take a deep breath. Fill your lungs all the way.

  • While holding your breath, put the mouthpiece of the meter between your teeth. Close your lips tightly around it, making a tight seal around the mouthpiece. Be sure your tongue does not block the hole.

  • Blow into the mouthpiece once, as hard and fast as you can. Your peak flow meter will measure how fast you can blow air out.

  • Take the meter out of your mouth.

  • Check where the marker has moved to on the numbered scale. Write this number down.

Step 3

  • Move the marker back to 0. Repeat the above steps 2 more times.

  • Write down the highest of the three numbers. This is your peak flow number.

Follow-up with your provider

As soon as you can, make follow-up appointments as directed by our staff.

 When to get immediate medical help

Call 911 right away if you have:

  • Shortness of breath that is not relieved by your quick-relief medication

  • Trouble walking and talking because of shortness of breath

  • Blue lips or fingernails

  • Severe wheezing

  • A peak flow reading less than 50 percent of your personal best