Lung Capacity Calculator
Lung capacity tests are among the most common clinical measurements used to assess respiratory health. Predicted values for spirometry measurements such as forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) are derived from reference equations that account for age, height, and sex. This calculator uses reference equations consistent with the Global Lung Function Initiative (GLI-2012) guidelines, endorsed by the American Thoracic Society (ATS) and European Respiratory Society (ERS). Enter your age, height, and sex to see your predicted FVC, FEV1, and total lung capacity estimate, along with context for interpreting actual spirometry results against the predicted values.
Predicted FVC reference equations (approximate, GLI-2012 derived)
Male FVC (L) = -4.80 + 0.000194 x (Height cm)^2 - 0.020 x Age
Female FVC (L) = -3.59 + 0.000141 x (Height cm)^2 - 0.018 x Age
FEV1 approx = FVC x 0.80 (males) or 0.82 (females)
TLC approx = FVC / 0.75
These are simplified approximations. Precise clinical values require full GLI-2012 software with race/ethnicity correction.
Lung capacity: frequently asked questions
What is total lung capacity (TLC)?
Total lung capacity is the maximum volume of air the lungs can hold after a maximum inhalation. In healthy adults it ranges from about 4 to 6 litres. TLC comprises vital capacity (the air you can exhale after a maximum breath in) plus residual volume (air that always remains in the lungs).
What is forced vital capacity (FVC)?
Forced vital capacity is the total volume of air you can exhale forcefully after a maximum inhalation. It is measured in litres and is the primary spirometry measurement. FVC declines with age, shorter height, and in conditions such as COPD, asthma, and fibrosis.
Which reference equations does this calculator use?
This calculator uses the GLI-2012 reference equations for adults (Global Lung Function Initiative, endorsed by the American Thoracic Society and European Respiratory Society), which provide predicted values by age, height, and sex for spirometry measurements across the lifespan.
What percentage of predicted is normal?
A measured FVC or FEV1 of 80% or more of the predicted value is generally considered within the normal range. Values between 70-79% are mildly reduced, 60-69% moderately reduced, and below 60% are severely reduced. Consult a pulmonologist for clinical interpretation.
What conditions reduce lung capacity?
Lung capacity is reduced by obstructive diseases (COPD, asthma, bronchiectasis) and restrictive diseases (pulmonary fibrosis, obesity, chest wall deformity, neuromuscular disease). Smoking is the leading cause of reduced lung function. Regular aerobic exercise can maintain and improve lung function.
Official sources
- American Thoracic Society / European Respiratory Society: Standardisation of Spirometry (2005).
- National Heart, Lung, and Blood Institute: Lung Function Tests.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.