Pulmonology• Updated 21 October 2026
Peak Flow Test
A simple test with a handheld meter that measures how fast you can blow air out, used to monitor asthma.
Results: Immediately
Quick Summary
Primary Purpose
To monitor asthma control at home and spot attacks early.
What It Measures
Peak expiratory flow rate.
Preparation
No preparation.
Overview
Your best reading guides your asthma action plan.
A falling peak flow can warn of worsening asthma.
What It Measures
Peak flow
Fastest speed of breathing out.
How It's Performed
- 01
Stand
And take a deep breath.
- 02
Blow
As hard and fast as possible into the meter.
- 03
Record
Best of three readings.
Interpreting Results & Next Steps
Discuss with Doctor
Your doctor will explain the report and what happens next.
If values are Low:
Readings below 50% of your best are a sign of a severe attack: follow your action plan and seek help.
Sources and further reading
Last updated 21 October 2026. For more detail, see these trusted health organisations.
- Lung Function Tests(opens in a new tab) · MedlinePlus, US National Library of Medicine
- Peak flow test(opens in a new tab) · NHS