Vital capacity $\left(\text{VC}\right)$ : The maximum volume of air a person can breathe in after a forceful expiration or the maximum volume of air a person can breathe out after a forceful inspiration is called vital capacity.

$\mathrm{V}\mathrm{C}\mathrm{ }=\mathrm{ }\mathrm{E}\mathrm{R}\mathrm{V}+\mathrm{T}\mathrm{V}+\mathrm{I}\mathrm{R}\mathrm{V}\mathrm{ }\mathrm{o}\mathrm{r}\mathrm{ }\mathrm{E}\mathrm{C}+\mathrm{I}\mathrm{R}\mathrm{V}\mathrm{ }\mathrm{o}\mathrm{r},\mathrm{ }\mathrm{I}\mathrm{C}+\mathrm{E}\mathrm{R}\mathrm{V}$

Inspiratory capacity: It is the total volume of air that a person can inspire after a normal expiration.