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Lung function

Spirometry results decoded

FEV1, FVC, ratios and percent predicted - how to read the numbers on your breathing test report.

Key facts

At a glance

  • FEV1: air expelled in the first second - the workhorse number for grading obstruction and tracking change over time.

  • FVC: the total volume you can force out; reduced FVC with a normal ratio suggests restriction rather than obstruction.

  • The ratio: FEV1/FVC below about 0.70 defines airway obstruction, the pattern of asthma and COPD.

  • Percent predicted: your values are compared with people of your age, sex, height and ethnicity - 80-120% is broadly normal.

  • Follow-up: patterns need clinical context - a respiratory specialist or GP maps yours to diagnosis and treatment.

The full picture

What this test involves, and how to get it

A spirometry report is three numbers and a comparison. FEV1 is the air you forced out in the first second; FVC is the total you forced out; and the FEV1/FVC ratio is the shape of the blow. A ratio below roughly 0.70 means airflow obstruction - air can get out only slowly - which is the shared signature of asthma and COPD; the FEV1 percent-predicted then grades that obstruction from mild to very severe. A normal ratio with a reduced FVC suggests restriction - the lungs cannot fill properly - which points towards scarring, chest wall or muscle problems and usually earns fuller lung function testing. Each value is expressed against predicted norms for your age, sex, height and ethnicity, with 80-120% of predicted broadly normal.

Distinguishing asthma from COPD leans on reversibility: a substantial FEV1 improvement after bronchodilator favours asthma, while fixed obstruction in a smoker favours COPD - though overlap exists and the history arbitrates. Normal spirometry with ongoing symptoms does not close the case either; asthma can hide between attacks, which is where FeNO testing and peak flow diaries come in. Reports also track disease: the FEV1 slope across years measures decline and treatment response. If your printout arrived without explanation, a results consultation - with your GP, or privately with a respiratory physician typically within a week - turns three numbers into an actual plan.

A quiet reminder

This guide is for information, not medical advice.

Your own clinician knows your history and can tell you which parts apply to you. Next review of this page: 2027-09-27.

Frequently asked

Common questions about Spirometry results decoded.

Quick, plain-English answers to what people ask us most.

  • What is Spirometry results decoded?

    Spirometry results decoded is a diagnostic test used to look at a specific part of the body or how it is functioning, helping doctors reach a clear diagnosis. It is usually requested when symptoms, an examination finding, or an earlier test result needs further investigation. Your doctor can explain exactly why it has been suggested in your case.

  • Why would a doctor order Spirometry results decoded?

    Doctors typically request this test to confirm or rule out a suspected condition, investigate unexplained symptoms, or monitor something that has already been diagnosed. It gives more detailed information than a standard examination alone can provide. The result helps guide what treatment or further investigation, if any, is needed.

  • Do I need to prepare for Spirometry results decoded?

    Preparation requirements vary by test; some need no special preparation, while others ask you to avoid caffeine, certain medications, or strenuous exercise beforehand. You will normally be given specific instructions when the appointment is confirmed. If anything is unclear, it is best to check directly with the clinic beforehand.

  • What happens during Spirometry results decoded?

    You will be asked to carry out a series of simple, guided steps - such as breathing into a device, lying still while readings are taken, or performing light activity - while equipment records the relevant measurements. The person carrying out the test will explain each stage as you go. Most appointments are completed within a single visit.

  • Does Spirometry results decoded hurt or carry risks?

    These tests are generally safe and non-invasive, with little to no discomfort involved. Any risks are usually minimal and will be explained to you before the test if relevant. Tell the team if you have any concerns so they can address them directly.

  • How long do results take?

    Results are usually reported by a specialist within a few days, though this can vary depending on the complexity of the test and whether further analysis is needed. You will normally be told when and how to expect your results at the time of booking. Urgent findings are typically flagged and communicated more quickly.

  • What do abnormal results mean, and what happens next?

    An abnormal result does not automatically mean something serious - it simply indicates that further assessment may be needed. Your doctor will review the findings in the context of your symptoms, history, and any other test results before recommending next steps, which might include further investigation, referral to a specialist, or reassurance that no action is needed. Always discuss your specific results with a doctor rather than interpreting them alone.

  • Is Spirometry results decoded available privately, or should I wait for the NHS?

    Spirometry results decoded can usually be arranged privately, often within days, with results reviewed by a specialist rather than waiting for routine NHS scheduling, which can take considerably longer depending on local demand. Cost varies by provider, and many private providers accept both self-referral and GP or specialist referral. Your GP can also advise on the appropriate NHS pathway if you would prefer to wait.

  • Is Spirometry results decoded accurate and reliable?

    This is a well-established test used routinely in clinical practice, and when performed and interpreted by an experienced specialist it is generally considered reliable. As with any test, results are always interpreted alongside your symptoms and medical history rather than in isolation. Occasionally a test may need to be repeated or supplemented with further investigation for a fully clear picture.

  • How do I book Spirometry results decoded privately, and how quickly can I be seen?

    You can typically book privately with or without a GP referral, and appointments are often available within a matter of days. A specialist reviews and reports the results, with a clear explanation of what they mean and any recommended next steps.