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. Your healthcare provider may want you to just take peak flow measurements as noted below. Or your provider may want the readings to be part of your Asthma Action Plan.

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 2 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. There are several types of peak flow meters that look different but do the same thing. The instructions below apply to all peak flow meters.

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 healthcare provider

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

Call 911

Call 911 right away if you have:

  • Shortness of breath that does not get better after using your quick-relief medicine

  • Trouble walking and talking because of shortness of breath

  • Blue lips or fingernails

  • Severe wheezing

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