Peak flow test
How to measure your peak flow
The first time your peak flow is measured, you'll be taught how to do it by a doctor or nurse. Thereafter, they may advise you to carry out the test regularly at home using your own peak flow meter.
To measure your peak flow:
- find a comfortable position, either sitting or standing
- ensure the meter is set to "0", your fingers are not obstructing the measurement scale, and the meter is held horizontally
- breathe in as deeply as you can and place your lips tightly around the mouthpiece
- breathe out as quickly and as hard as you can
- when you've finished breathing out, make a note of your reading
This should be repeated three times, and the highest of the three measurements should be recorded as your peak flow score.
If you're monitoring your asthma at home, you may have a diary or chart to record your score. You can download a peak flow diary (PDF, 2.2Mb) from the Asthma UK website if you don't have one.
Medically Reviewed by a doctor on 21 Dec 2018
Introduction
Peak flow is a simple measurement of how quickly you can blow air out of your lungs. Read about why and how it's measured.
Why peak flow is measured
By measuring how fast you're able to breathe out, your peak flow score can indicate whether your airways are narrowed. This could be a sign that you have Asthma , although other tests such as spirome
How to measure your peak flow
The first time your peak flow is measured, you'll be taught how to do it by a doctor or nurse. Thereafter, they may advise you to carry out the test regularly at home using your own peak flow meter.
Your peak flow score
Your peak flow score also known as your peak expiratory flow (PEF) will be displayed on the side of your peak flow meter. This is given in litres of air breathed out per minute (l/min). What's consid
What to do ifyour peak flow is low
If you have a personal asthma action plan, itmight say what you should do when your peak flow score falls to a certain level. You mayjust need to use one of your inhalers, or you may need to seek med
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