Human Physiology • Respiratory Physiology
This calculator builds the standard lung volume compartments and combines them into clinically useful capacities such as IC, FRC, VC, and TLC.
Use one pattern, compare two patterns, or paste/upload CSV rows with label,tv,irv,erv,rv,unit to add extra states to the comparison chart.
Lung volumes are the basic compartments such as tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume. Lung capacities are combinations of those volumes, such as IC, FRC, VC, and TLC.
Inspiratory capacity is calculated as tidal volume plus inspiratory reserve volume. Functional residual capacity is calculated as expiratory reserve volume plus residual volume.
Residual volume is the air that remains after maximal expiration, so it cannot be exhaled voluntarily. A relatively large residual volume can occupy a greater fraction of total lung capacity and reduce the usable excursion represented by vital capacity.
Total lung capacity is the sum of inspiratory reserve volume, tidal volume, expiratory reserve volume, and residual volume. In plain form, TLC = IRV + TV + ERV + RV.
This calculator is useful for learning how standard lung compartments combine into clinically important capacities and for comparing normal, restrictive-like, and obstructive-like patterns. It is not a full diagnostic spirometry interpretation system on its own.