\[\text{Volumetric Strain} =\frac{\text{Change in Volume}(\delta \text{V})}{\text{Original Volume}(\text{V})}\]\[\varepsilon ={{\varepsilon }_{1}}+{{\varepsilon }_{2}}+{{ \varepsilon }_{3}}\]\[\text{Volumetric Strain} =\frac{\left( {{\sigma }_{1}}+{{\sigma }_{2}}+{{\sigma }_{3}} \right)(1-2\mu )}{E}\]