Registered Nurses' Association of Ontario

Finding the Personal Best Peak Flow Number

A person’s personal best peak flow number is the highest peak flow number achieved over a two- to three-week period when asthma is controlled.

Each person’s asthma is different, and one person’s “best” peak flow value may be higher or lower than another person’s of the same height, weight, and sex. The action plan needs to be based on the person’s personal best peak flow value.

To identify the personal best peak flow number, the person should take peak flow readings:

  • At least twice a day for 2 to 3 weeks,
  • Upon awakening and before bed, and
  • Prior to and 15 minutes after taking a short-acting inhaled bronchodilator (reliever).


Chronic Disease
Adult Asthma Care Guidelines for Nurses: Promoting Control of Asthma
Point of Care Resources