# Mass vs. Volume

**Difference Between Mass and Volume**

The mass and volume are the fundamental properties of matter and these two properties are related to each other. The mass is proportional to the volume when density remains constant. If a matter has a volume, then it also has a mass.

**Mass**

Mass is a property of matter which is a measure of inertia. It also gives an idea about how much matter is present in the object. Out of the three fundamental dimensions (M) of mechanics, mass is one with time – T and length – L being the other two. The SI unit (International System of Units) for the mass is ‘kilogram’ denoted as Kg. However, units like gram, milligram to metric tons are used in appropriate situations. The Imperial system of units (also known as British units) was pound, grain and stone to measure the mass.

Usually we take the mass as a property which is immutable. The mass of an object will remain same on the earth, the moon or anywhere. However, the mass can show some changes at higher speeds according to the theory of relativity which was proposed by Albert Einstein. Another theory states that the mass can be converted into energy and his principle is widely used in generation of nuclear energy.

**Volume**

Volume is a measurement of the three-dimensional which is space occupied by any object. The unit of measurement of the volume is ‘cubic meter’. However, ‘liter’, which is equal to one thousandth of a cubic meter (cubic decimeter or) is most popular unit of measurement for the volume. The gallon, ounce and pint are the units of volume in the imperial system that were used prior to the SI system came into existence. One milliliter equals one cubic centimeter and the volume has dimensions of L3 (length x length x length).

Unlike the mass, the volume changes according to the external conditions. As an example, the volume of a gas sample depends on air pressure. The volume of a solid can be changed when it is melted.

There are mathematical expressions to calculate the volume of general forms (length x height x width for a cuboids and 4 / 3 x R3 for a sphere). For objects with complicated shapes the volume can be measured by the amount of fluid displaced by the object and then measuring the volume of the fluid.