$$P=\frac{h^2}{20m_em_p^{5/3}}\left(\frac{3}{\pi}\right)^{2/3}\left(\frac{\rho}{\mu_e}\right)^{5/3}$$
where:
P	=	pressure
h	=	Planck's constant
me	=	mass of electron
mp	=	mass of proton
ρ	=	density
μe	=	electron/proton ratio