Vital Capacity Calculator
This calculator estimates your predicted vital capacity (VC) - the maximum volume of air you can breathe out after a full inhalation - using the validated Berglund equations that take your sex, age and height as inputs. You can also enter your measured spirometry volumes (IRV, TV, ERV, and optionally RV) to compute VC directly and derive the full set of standard lung capacities. Switch between metric and imperial units; results update instantly.
What is vital capacity?
Vital capacity (VC) is the total volume of air a person can exhale after taking the deepest possible breath. It is the sum of three primary lung volumes: the inspiratory reserve volume (the extra air you can inhale beyond a normal breath), the tidal volume (the air moved with each normal resting breath), and the expiratory reserve volume (the extra air you can push out after a normal exhale). VC does not include the residual volume, the air that always remains in the lungs after a maximal exhale. In healthy non-smoking adults VC typically ranges from 3 to 5 litres, with men and taller individuals generally showing higher values.
How the predicted vital capacity formula works
The prediction equations used here are from Berglund et al. (1963), which remain widely used reference equations in clinical pulmonology. The formula takes into account sex, standing height and age. For men the equation is: VC (cm3) = height (cm) x (27.63 - 0.112 x age). For women: VC (cm3) = height (cm) x (21.78 - 0.101 x age). Dividing the result by 1000 gives litres. The negative age coefficient reflects the gradual decline in lung function with advancing age, approximately 20-30 mL per year in healthy adults. Height is the dominant predictor because taller people have larger thoracic cavities.
Spirometry components and how they relate to vital capacity
A standard spirometry test directly measures VC alongside forced vital capacity (FVC), which is exhaled as fast as possible. The four primary lung volumes that summate to total lung capacity (TLC) are: tidal volume (TV), inspiratory reserve volume (IRV), expiratory reserve volume (ERV), and residual volume (RV). Spirometers can measure TV, IRV and ERV directly. RV must be estimated indirectly by body plethysmography, helium dilution, or nitrogen washout. From these four volumes, four lung capacities are derived: VC = IRV + TV + ERV; inspiratory capacity (IC) = IRV + TV; functional residual capacity (FRC) = ERV + RV; and total lung capacity (TLC) = VC + RV.
Clinical interpretation and limitations
A measured VC that is less than 80% of the predicted value is generally considered abnormal and warrants further evaluation. Reduced VC is a classic sign of restrictive lung disease (such as pulmonary fibrosis, pleural effusion, or neuromuscular weakness of the respiratory muscles). In obstructive lung disease (such as asthma or COPD), VC is often near normal early in the disease but the forced expiratory volume in one second (FEV1) is disproportionately reduced. The Berglund prediction equations were derived from European populations and may not perfectly fit individuals of other ethnicities; the Global Lung Function Initiative (GLI) reference equations incorporate ethnicity corrections for more precise predictions. This calculator is intended as an educational reference tool and cannot replace a clinical spirometry assessment.
Normal adult lung volume reference ranges
| Volume / Capacity | Symbol | Typical range (L) | Clinical significance |
|---|---|---|---|
| Tidal Volume | TV | 0.4 - 0.6 | Air per normal breath |
| Inspiratory Reserve Volume | IRV | 1.9 - 3.3 | Extra air above a normal breath |
| Expiratory Reserve Volume | ERV | 0.7 - 1.2 | Extra air below a normal breath |
| Residual Volume | RV | 1.0 - 1.5 | Air that cannot be exhaled |
| Vital Capacity | VC | 3.0 - 5.5 | IRV + TV + ERV |
| Inspiratory Capacity | IC | 2.0 - 3.8 | IRV + TV |
| Functional Residual Capacity | FRC | 1.8 - 2.8 | ERV + RV |
| Total Lung Capacity | TLC | 5.0 - 7.5 | VC + RV |
Approximate normal ranges for healthy non-smoking adults. Values vary with age, sex, height and ethnicity. Source: European Respiratory Society reference equations.
Frequently asked questions
What is a normal vital capacity for adults?
In healthy non-smoking adults, vital capacity typically falls between 3 and 5 litres. Men tend to have higher values than women (around 4-5 L vs 3-4 L on average) because of their larger average height and thoracic dimensions. Athletes and very tall individuals can exceed 6 L. Values are considered low if they fall below 80% of the predicted value for a person of the same sex, age and height.
What is the difference between vital capacity and total lung capacity?
Vital capacity is the maximum air you can move in or out of your lungs (IRV + TV + ERV), but it excludes the residual volume - the air that always stays in your lungs and keeps the alveoli from collapsing. Total lung capacity (TLC) is VC plus the residual volume and represents the absolute maximum air your lungs can contain. A typical adult has a TLC of around 5 to 7 L, of which roughly 1 to 1.5 L is residual volume.
Can I improve my vital capacity with exercise?
Regular aerobic exercise, particularly swimming and activities that demand large sustained breathing efforts, can help maintain or modestly increase vital capacity by strengthening the respiratory muscles (diaphragm and intercostals) and improving chest wall compliance. The effect is most pronounced in previously sedentary individuals. While you cannot permanently expand your lungs, trained athletes regularly show VCs 10-20% higher than sedentary adults of the same age, sex and height. Breathing exercises such as pursed-lip breathing and diaphragmatic breathing are commonly used in pulmonary rehabilitation to maximise functional capacity.
Why does vital capacity decline with age?
Several changes combine to reduce VC with age: the rib cage becomes stiffer, the respiratory muscles weaken, the diaphragm loses some elasticity, and the lung parenchyma loses recoil. The average decline is roughly 20-30 mL per year after the mid-20s, so a 70-year-old man might have a predicted VC about 1-1.5 L lower than the same man at age 25. This is why the Berglund equations include an age term with a negative coefficient.
What is the difference between VC and FVC?
Vital capacity (VC) is measured with a slow, complete exhalation, giving the lungs time to empty fully. Forced vital capacity (FVC) requires the patient to exhale as hard and fast as possible. In healthy individuals the two values are very similar. In obstructive lung disease (such as COPD or asthma), air trapping during a forced manoeuvre can make FVC lower than slow VC - this difference is itself a diagnostic clue. In restrictive disease, both VC and FVC are reduced proportionally.