<P> Volume is the quantity of three - dimensional space enclosed by a closed surface, for example, the space that a substance (solid, liquid, gas, or plasma) or shape occupies or contains . Volume is often quantified numerically using the SI derived unit, the cubic metre . The volume of a container is generally understood to be the capacity of the container; i.e., the amount of fluid (gas or liquid) that the container could hold, rather than the amount of space the container itself displaces . </P> <P> Three dimensional mathematical shapes are also assigned volumes . Volumes of some simple shapes, such as regular, straight - edged, and circular shapes can be easily calculated using arithmetic formulas . Volumes of a complicated shape can be calculated by integral calculus if a formula exists for the shape's boundary . Where a variance in shape and volume occurs, such as those that exist between different human beings, these can be calculated using three - dimensional techniques such as the Body Volume Index . One - dimensional figures (such as lines) and two - dimensional shapes (such as squares) are assigned zero volume in the three - dimensional space . </P>

Which si unit is used to measure volume