How do you convert psig to psia?

To convert psig (pounds per square inch gauge) to psia (pounds per square inch absolute), you need to add the atmospheric pressure to the psig value. Atmospheric pressure is typically about 14.7 psi at sea level. Therefore, the formula is: psia = psig + 14.7 psi. For example, if you have 30 psig, the conversion to psia would be 30 + 14.7 = 44.7 psia.