This site is intended for healthcare professionals

Go to /sign-in page

You can view 5 more pages before signing in

Peak expiratory flow (PEF)

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

The PEFR is the maximum rate of airflow that can be achieved during a sudden forced expiration form a position of full inspiration.

The good points about PEFR are:

  • the PEFR reflects the calibre of the airways and is most useful for day-to-day monitoring of asthma
  • the PEFR device is cheap and convenient

The bad points about PEFR are that the value depends on:

  • effort
  • technique

Also PEFR is a measure of airflow and cannot detect restrictive ventilatory defects, such as those caused by pulmonary fibrosis, since these reduce lung volume but do not affect airflow (1).

Click here to download the normal adult values chart

Click here to download the normal paediatric values chart


  1. The Practitioner 2005; 249:180-88.

Related pages

Create an account to add page annotations

Add information to this page that would be handy to have on hand during a consultation, such as a web address or phone number. This information will always be displayed when you visit this page