Lung Capacity Estimator
Estimate predicted lung capacity and FEV1 from age, height, and sex using Quanjer equations.
Returns comparison to normal spirometry values for lung health.
Lung capacity (FVC) estimation predicts your Forced Vital Capacity — the maximum volume of air you can exhale in a single breath — based on age, height, sex, and ethnicity using validated spirometry reference equations.
Predicted FVC formulas (Knudson equations, widely used in clinical practice):
Males: FVC (liters) = (0.0576 × Height in cm) − (0.0269 × Age) − 4.34
Females: FVC (liters) = (0.0443 × Height in cm) − (0.0197 × Age) − 2.89
Important note: Reference equations differ by population. The Global Lung Initiative (GLI-2012) equations are now the international gold standard and include ethnicity adjustments.
Predicted FVC values by age and height (males):
| Age | 165 cm (5'5") | 175 cm (5'9") | 185 cm (6'1") |
|---|---|---|---|
| 25 | 4.7 L | 5.3 L | 5.8 L |
| 40 | 4.3 L | 4.9 L | 5.4 L |
| 55 | 3.9 L | 4.5 L | 5.0 L |
| 70 | 3.5 L | 4.1 L | 4.6 L |
Lung function interpretation (% of predicted FVC):
| % Predicted | Interpretation |
|---|---|
| 100%+ | Excellent |
| 80–99% | Normal range |
| 70–79% | Mild restriction |
| 60–69% | Moderate restriction |
| Below 60% | Severe restriction — medical evaluation needed |
Worked example: Male, 42 years old, 178 cm tall. FVC = (0.0576 × 178) − (0.0269 × 42) − 4.34 FVC = 10.25 − 1.13 − 4.34 = 4.78 liters predicted
If spirometry measures 3.8 L: 3.8 ÷ 4.78 = 79.5% of predicted → Mild restriction
Factors that reduce FVC: smoking, obesity, scoliosis, neuromuscular disease, pulmonary fibrosis. Factors that increase FVC: athletic training (especially swimming and endurance sports), tall stature, younger age. Regular aerobic exercise can maintain lung capacity significantly better into older age.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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