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FEV1 % predicted

Breathing tests · also printed as FEV1 % pred, FEV1 percent predicted, FEV1 %pred, FEV1 (% predicted), FEV1 percentage predicted

Typical UK adult range80 % and above

80 percent and above is typical; lower bands are printed by the lab.

What this test measures

This expresses FEV1 as a percentage of the value predicted for someone of the same age, sex, height and ancestry.

Why doctors request it

The number most often quoted when grading how severe asthma or COPD is.

What commonly pushes it up

There is no problem with a high value

What commonly pushes it down

Airway narrowing
Stiff lungs
Poor effort

Everyday reasons for a value outside the range

Different reference equations give different predicted values, so the percentage can shift between labs

About the sample

Read with the ratio to know which pattern is present.

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

Got a report with FEV1 % predicted 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.