How to Calculate Density from Mass and Volume

Calculates density as mass ÷ volume. Mass is in kilograms, volume in m³, and density in kg/m³.

Explanation

Density is mass per unit volume. Of two objects the same size, the denser one is the heavier.

\rho = \dfrac{m}{V}

$\rho$ (rho) is the density, in kg/m³
$m$ is the mass, in kilograms (kg)
$V$ is the volume, in cubic metres (m³)

Density belongs to the material rather than to the lump. Take one litre of water or take ten, and the density is the same.

Example

The defaults are a mass of 10 kg and a volume of 2 m³.

\rho = \dfrac{10}{2} = 5\,\mathrm{kg/m^3}

The density is 5 kg/m³.

Notes

Watch the units. The two common ones, g/cm³ and kg/m³, differ by a factor of 1000: 1 g/cm³ = 1000 kg/m³. Water is 1 g/cm³, which is the same as 1000 kg/m³. Enter kilograms and cubic metres here and the answer comes out in kg/m³.

The volume cannot be zero, since that would mean dividing by zero.

Anything less dense than water (1000 kg/m³) floats on it, and anything denser sinks. Ice, at about 917 kg/m³, floats. Iron, at about 7870 kg/m³, does not.

Materials expand as they warm, so density shifts a little with temperature. Precise work has to say at what temperature a figure holds.