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What's a Peak Flow Meter?

Medically reviewed by: KidsHealth Medical Experts

A peak flow meter is a portable handheld device used to measure how well a person with asthma can blow air out of the lungs. (Asthma narrows the airways, making breathing difficult.) The person blows into the meter and then checks the reading.

Some people with asthma use a peak flow meter at home to see how well their asthma is being controlled. The meter can tell if the airways are getting narrow even before symptoms start.