Compressibility factor

The compressibility factor, $Z$, is given by

$Z=\frac{pV}{N{k}_{B}T}$

where p is the pressure, V is the volume, $k_B$ is the Boltzmann constant, T is the temperature and N is the number of molecules.

Compressibility factor of an Ideal Gas

From the ideal gas law we see that

$Z=\frac{pV}{N{k}_{B}T}=1$