# Is the density of a unit cell same as the density of the substance?

Yes, the density of a unit cell is the same as the density of the substance.

### Unit cell

The mass of a unit cell is equal to the product of the number of atoms in a unit cell and the mass of each atom in the unit cell.  For real crystals with defects, the density can be slightly different due to vacancies, dislocations, grain boundaries etc.

The density of a Unit Cell will be D = Mass/Volume

The number of atoms will depend on the kind of cell it is. To obtain the mass of a unit cell, we multiply the number of atoms ‘n’ into the mass of each atom ‘m’.

Mass of Unit Cell = m × n