Specific Gravity of a gas can be calculated as
_{\(SG = {\rho \over \rho air}\)}
where
SG = specific gravity of Gas
ρ = density of gas (kg/m3)
ρair = density of air (kg/m3)
* In a normal condition, air is defined at 20oC and 1 atm and density of air is 1.205 kg/m3 is used.