density is (mass / volume). But what is (mass / area)? For example, if I wanted to know the mass of how much water would fill a jar, it would be mass = (volume of jar * density of water) = cubic length * (mass / cubic length.) But imagine I knew how much a square meter of paint weighed, even if I did not know the thickness of a coat of paint. If I wanted to know the mass of how much paint it would take to cover a wall 10x10 meter wall, it would be mass = (area of wall * ??) = squared length * (mass / squared length). mass / cubed length = density mass / squared length = ?? Is there such a term?