Since the gravity at the surface of Mars is about 38 percent of Earth's, this means that the same column of air on Mars would have a weight 38 percent less than on the Earth. So, if you could pressurize the martian atmosphere with the same number of atoms as on the Earth, I would imagine that the total pressure would be 0.38 times Earth's sea level pressure which is about 30 inches of mercury or 1013 millibars. The martian maximum air pressure would be about 380 millibars for the same atmospheric density, and this may not be stable since it would be leaking away rather rapidly. I'm not an expert on these matters but this seems logical to me.