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FEV1

Breathing tests · also printed as FEV1 (L), Forced expiratory volume in 1 second, FEV 1, FEV1 litres, Forced expiratory volume

Typical UK adult rangeNo single typical range

No fixed range; the report prints a predicted value and a percent of predicted.

What this test measures

FEV1 is the volume of air blown out in the first second of a hard, fast breath out. It is the main measure of how open the airways are.

Why doctors request it

Used to assess and follow asthma and COPD, and before some operations. Compared with a predicted value for age, sex, height and ancestry.

What commonly pushes it up

There is no problem with a high value

What commonly pushes it down

Narrowed airways, as in asthma and COPD
Stiff lungs or a weak chest wall
Poor technique or effort on the day
A chest infection

Everyday reasons for a value outside the range

The predicted value depends on age, sex, height and ancestry, so the absolute number means little on its own
Technique and effort matter a great deal
Values fall gently with age

About the sample

Read alongside FVC, the ratio and the percent predicted.

Written by a UK consultant physician. Typical UK adult reference ranges; your laboratory's own printed range takes precedence.

Got a report with FEV1 on it?

Upload a photo or PDF and see every line against the range your lab printed, explained in plain English. First report free.

Read my report free

This is an educational summary of results you uploaded. It is not medical advice, a diagnosis or a treatment plan, and it does not replace the doctor who requested the test. If you are worried, or a result is marked outside range, discuss it with your doctor. Written and reviewed by a UK consultant physician. Reference ranges vary between laboratories.