Each unit cell of $\mathrm{NaCl}$ consists of 4 chloride ions and
 

The crystal structure of sodium chloride, it is composed of face-centered cubic unit cells. The octahedral voids are occupied by sodium ions, which are smaller, where as chloride ions, which are relatively larger in size, are found on the corners and centres of each face of the NaCl unit cell.

There are 14 chloride ions in each unit cell of the NaCl lattice because there are 13 octahedral positions (12 edge centres and 1 body centre) and 13 octahedral positions (12 edge centres and 1 body centre). As a result, there are 14 chloride ions and 13 sodium ions in each unit cell of NaCl.

Unit cell of NaCl contains 4:4 Na⁺ and Cl^-