Density Conversion Calculator

Density is defined as mass divided by volume: rho = m/V. It is an intensive property, meaning it does not depend on the amount of material. Pure water at 4 degrees C has a density of exactly 1000 kg/m^3 (1.000 g/cm^3), which was historically used to define the gram. The SI unit kg/m^3 is used in physics and engineering calculations (fluid dynamics, structural analysis, thermodynamics). The CGS unit g/cm^3 is common in chemistry, geology, and materials science because many common materials have densities near 1-20 g/cm^3, making values easy to remember. The unit g/mL is numerically identical to g/cm^3 because 1 mL = 1 cm^3. Imperial units (lb/ft^3) are used in US construction, HVAC, and oil industry applications. The conversion factor is 1 lb/ft^3 = 16.0185 kg/m^3. Specific gravity is a related dimensionless quantity: the ratio of a substance's density to that of water at a reference temperature. For practical purposes, specific gravity in CGS units equals density in g/cm^3 (since water is 1.000 g/cm^3 at 4C). Temperature and pressure affect density. Gases are highly compressible and their density varies linearly with pressure and inversely with temperature (ideal gas law). Liquids and solids are nearly incompressible but still expand slightly when heated. Water is unusual in that it reaches maximum density at 4 degrees C, becoming less dense as it approaches 0 degrees C (which is why ice floats). In industrial applications, density measurements are used for quality control (verifying purity of chemicals), process control (monitoring concentration in real time), and safety (ensuring gases remain below explosive concentrations).