Matter can also be described by measuring its density. Density is the mass of an object in a given volume. To calculate density, divide an object’s mass by its volume. The unit for density is grams per cubic centimeter. For example, a piece of aluminum with a mass of 500 g and volume of 200 cm3 has a density of 2.5 g/cm3. A piece of iron with the same volume has a mass of 1500 g. Iron’s density is 7.5 g/cm3.