# What is Density, Specific Weight, Specific Volume and Specific Gravity?

### What is Inside?

- Density or mass density,
- Specific weight,
- Specific volume and
- Specific gravity

### Density or Mass Density:

Density (mass density) of a fluid is defined as the ratio of mass of a fluid to the volume of the fluid. In other words it is defined as the mass per unit volume of a fluid.

### Specific Weight:

Specific weight of a fluid is defined as the ratio of the weight of a fluid to the volume of the fluid. Or weight of a fluid per unit volume is called its specific weight.

### Specific Volume:

Specific volume of a fluid is defined as the ratio of the volume of a fluid to the mass of the fluid. In other words it may also be defined as volume per unit mass of a fluid.

### Specific Gravity:

Specific gravity is defined as the ratio of the density of a fluid to the density of a standard fluid. For liquids, water is taken as the standard fluid where as for gases air is taken as the standard fluid. It is denoted by the symbol S.

- The density of water is taken as 1000 kg/ cubic metre