Lung Age Calculator
"Lung age" is the age at which a healthy non-smoker of your height and sex would be expected to have your FEV1 — the amount of air you can blow out in one second. This calculator uses the published Morris & Temple (1985) equation, so it needs an FEV1 value from a real spirometry test. It does not guess lung age from lifestyle questions.
Before you start
Method : Published equation (Morris & Temple 1985) applied to a measured FEV1. No lifestyle points are added.
Validation : Formula checked against the paper's two worked examples. The equation itself has a large error (about ±16 years).
Review : not reviewed by a qualified clinician. Educational only — not a diagnosis or a medical test.
Only for adults aged 20–84 with a real spirometry result. If you are breathless, wheezy or coughing a lot, see a doctor instead.
Your answers stay in this browser tab; nothing is sent or stored.
Enter your spirometry FEV1, age, sex and height.
How to Use This Calculator
- Find FEV1 (in litres) on your spirometry report.
- Enter your age, sex and height.
- Press Calculate lung age.
Methodology & assumptions
Morris & Temple rearranged the spirometry prediction equations of Morris, Koski & Johnson (1971), derived from 988 healthy non-smoking adults aged 20–84, to solve for age (height H in inches, FEV1 in litres):
- Men: lung age = 2.870 × H − 31.250 × FEV1 − 39.375
- Women: lung age = 3.560 × H − 40.000 × FEV1 − 77.280
Centimetres are divided by 2.54. The result is shown to the nearest year with no adjustments.
Worked examples
From the paper (Fig. 4): man, 57, 68 in, FEV1 2.54 L → 2.87×68 − 31.25×2.54 − 39.375 = 76.4. The paper describes him as about 20 years older than his age.
From the paper (Fig. 3): man, 54, 69 in, FEV1 3.30 L → 55.5. The paper calls this lung age "identical" to his age; the 1.5-year gap comes from rounding in the published coefficients.
Understanding your result
Treat lung age as a rough illustration. An error of ±15–16 years is normal for this equation, so small differences from your real age mean nothing. The reference group was healthy non-smokers tested in Oregon around 1970; it may fit people of other ancestries, body shapes or eras less well. It cannot diagnose asthma, COPD or any other condition.
Sources & further reading
- Morris JF, Temple W. Spirometric "lung age" estimation for motivating smoking cessation. Preventive Medicine 1985;14(5):655-662.
- Morris JF, Koski A, Johnson LC. Spirometric standards for healthy nonsmoking adults. Journal of Occupational Medicine 1971;13(7):360.
- Newbury W, Lorimer M, Crockett A. Newer equations better predict lung age in smokers. Primary Care Respiratory Journal 2012;21(1):78-84.
Frequently Asked Questions
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