$\begin{aligned} & \text { density }=\frac{\text { Mass }}{\text { Volume }} \\ & \text { SI unit of mass }=\mathrm{kg} \\ & \text { SI unit of volume }=\mathrm{m}^3 \\ & \text { SI unit of density }=\frac{\mathrm{kg}}{\mathrm{m}^3} \text { or } \mathrm{kg} \cdot \mathrm{m}^{-3}\end{aligned}$