Calculator Inputs
Use adult spirometry values. This page is educational and does not diagnose disease.
Formula Used
The calculator uses the classic FEV1-based lung-age equations, converted to centimetres for convenience.
| Group | Lung age equation | Predicted FEV1 at actual age |
|---|---|---|
| Male | Lung age = 1.130 × height(cm) − 31.25 × FEV1(L) − 39.375 | Predicted FEV1 = [1.130 × height(cm) − age − 39.375] ÷ 31.25 |
| Female | Lung age = 1.402 × height(cm) − 40.00 × FEV1(L) − 77.280 | Predicted FEV1 = [1.402 × height(cm) − age − 77.280] ÷ 40.00 |
Additional calculations
- FEV1/FVC ratio = measured FEV1 ÷ measured FVC
- FEV1 percent predicted = measured FEV1 ÷ predicted FEV1 × 100
- Pack-years = (cigarettes per day ÷ 20) × smoking years
- Age gap = estimated lung age − chronological age
How to Use This Calculator
- Enter sex, age, and height using centimetres or inches.
- Type the measured FEV1 and FVC values from spirometry.
- Add smoking information to estimate pack-years and context.
- Mark symptoms and whether values are post-bronchodilator.
- Press the calculate button to show the result above the form.
- Review lung age, age gap, ratio, and interpretation together.
- Use CSV or PDF export if you want a saved copy.
- Discuss abnormal results with a healthcare professional for full interpretation.
Example Data Table
| Sex | Age | Height (cm) | FEV1 (L) | FVC (L) | FEV1/FVC (%) | Lung age (years) | Comment |
|---|---|---|---|---|---|---|---|
| Male | 45 | 175 | 3.10 | 4.30 | 72.1 | 61.5 | Older than actual age by 16.5 years. |
| Female | 38 | 162 | 2.30 | 3.10 | 74.2 | 57.8 | Older than actual age by 19.8 years. |
| Male | 60 | 168 | 2.00 | 3.05 | 65.6 | 88.0 | Low ratio suggests medical review is worthwhile. |
Frequently Asked Questions
1. What does lung age mean?
Lung age translates an FEV1 result into an age-like value. It shows the age of a reference adult whose airflow is similar to the measured result. It is designed to make spirometry easier to understand, not to replace a formal clinical interpretation.
2. Can lung age diagnose COPD or asthma?
No. Lung age alone cannot diagnose COPD, asthma, or any other condition. Diagnosis needs proper spirometry quality checks, clinical history, and medical interpretation. A low FEV1/FVC ratio is only one part of the picture.
3. Why are height and sex required?
FEV1 reference equations depend heavily on body size and sex. Two people with the same airflow value can have different expected lung performance if their height or sex differs. That is why those fields matter to the calculation.
4. Why does the page ask for FVC too?
FVC is used to calculate the FEV1/FVC ratio. That ratio helps add screening context about possible airflow limitation. It also makes the result more informative than a lung-age number by itself.
5. What is a pack-year?
A pack-year estimates smoking exposure. One pack-year equals smoking 20 cigarettes per day for one year. This page calculates pack-years as cigarettes per day divided by 20, multiplied by years smoked.
6. Why can the calculated lung age seem extreme?
Older lung-age equations can produce very low or very high values when FEV1 is far from the reference range. To keep the display practical, this page limits the shown lung age to the adult range used here.
7. Should I use pre or post-bronchodilator values?
If you have a formal spirometry report, post-bronchodilator values are often more useful for interpretation of obstruction. Still, either result can be explored here for education. Use the checkbox so the note matches the test context.
8. When should I seek medical advice?
Seek medical advice if you have breathlessness, wheeze, chronic cough, frequent chest infections, or a low ratio on spirometry. Get urgent care for severe breathing trouble, bluish lips, or sudden worsening symptoms.