Calculate predicted total lung capacity, vital capacity, residual volume, and FRC by age, height, and sex. Visual breakdown of all lung volumes.
Total lung capacity (TLC) represents the maximum volume of air the lungs can hold after a full inspiration. It is the sum of all four lung volumes: tidal volume (VT), inspiratory reserve volume (IRV), expiratory reserve volume (ERV), and residual volume (RV). Normal TLC in adults ranges from about 4 to 6 liters in women and 6 to 8 liters in men, with height being the strongest determinant.
Understanding predicted lung volumes is fundamental to pulmonary medicine. While spirometry measures dynamic volumes (FVC, FEV₁), static volumes like TLC, RV, and functional residual capacity (FRC) require body plethysmography or gas dilution techniques. These measurements are essential for distinguishing restrictive lung diseases (where TLC is reduced below 80% predicted) from obstructive diseases (where TLC may be normal or increased due to air trapping). The **RV/TLC ratio** is particularly important — values above 30% suggest air trapping commonly seen in COPD and emphysema.
Predicted values vary primarily by height, age, sex, and ethnicity. Height has the single largest effect, as longer torsos contain more alveoli. Age causes gradual decline in elastic recoil, increasing RV while maintaining or slightly decreasing TLC. Sex differences reflect average body size and chest wall dimensions. This calculator estimates all major lung volumes and capacities using established prediction equations, providing a visual breakdown helpful for understanding respiratory physiology.
Understanding predicted lung volumes is essential for interpreting pulmonary function tests and distinguishing obstructive from restrictive lung disease. This calculator provides a complete volume breakdown with visual representation. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain. Use this clarification to avoid ambiguous interpretation. Align this note with review checkpoints.
Predicted values based on European Respiratory Society reference equations. Males: TLC = 7.99 × height(m) − 7.08; VC = 0.0576 × ht(cm) − 0.026 × age − 4.34; RV = 0.0216 × ht(cm) + 0.0207 × age − 2.84. FRC = ERV + RV. IC = TLC − FRC. VT ≈ 500 mL.
Result: TLC = 6.90 L
A 35-year-old male at 175 cm has a predicted TLC of ~6.90 L, vital capacity ~4.03 L, and residual volume ~1.35 L. The RV/TLC ratio of ~19.5% is well within normal limits.
Use consistent units, verify assumptions, and document conversion standards for repeatable outcomes.
Most mistakes come from mixed standards, rounding too early, or misread labels. Recheck final values before use. ## Practical Notes
Use this for repeatability, keep assumptions explicit. ## Practical Notes
Track units and conversion paths before applying the result. ## Practical Notes
Use this note as a quick practical validation checkpoint. ## Practical Notes
Keep this guidance aligned to expected inputs. ## Practical Notes
Use as a sanity check against edge-case outputs. ## Practical Notes
Capture likely mistakes before publishing this value. ## Practical Notes
Document expected ranges when sharing results.
Normal TLC varies widely: ~4–6 L for women and ~6–8 L for men. It depends primarily on height. TLC < 80% predicted suggests restrictive disease.
Residual volume is the air that remains in the lungs even after maximal exhalation — it cannot pass through the spirometer. Body plethysmography or gas dilution methods are needed.
RV/TLC > 30% suggests air trapping, commonly seen in COPD and emphysema. The patient cannot fully empty their lungs due to airway collapse during expiration.
Height is the strongest predictor of lung volumes. Taller individuals have larger thoracic cavities with more alveoli, resulting in proportionally larger TLC, VC, and other volumes.
Chronic smoking causes inflammation, loss of elastic recoil, and emphysematous destruction, which paradoxically may increase TLC (hyperinflation) while reducing VC and increasing RV. Use this as a practical reminder before finalizing the result.
TLC is the total air the lungs can hold. Vital capacity (VC = TLC − RV) is the air you can actually move in and out. RV remains trapped and unavailable for ventilation.