Density Converter
Convert density between kilograms per cubic metre, grams per cubic centimetre, pounds per cubic foot and pounds per cubic inch. Density is mass per unit volume, and the metric units line up neatly — water is almost exactly 1 g/cm³, which is 1000 kg/m³. The imperial units are exact conversions from the metric base, derived from the defined pound and inch. This is the property that decides whether something floats, how much a volume of material weighs, and how buoyancy behaves.
How to use this tool
- Enter a density value.
- Choose the unit you are converting from.
- Choose the unit you want the answer in.
- Read the result, or use “show every equivalent unit” to compare all of them.
- Remember 1 g/cm³ = 1000 kg/m³, a handy check on metric conversions.
The formula
Density is mass per unit volume, with the SI base unit kilogram per cubic metre. The gram-per-cubic-centimetre unit is convenient because water is almost exactly 1 g/cm³.
base_kg/m³ = value × (kg/m³ per unit)
result = base ÷ (kg/m³ per target)- kg/m³
- SI base unit of density
- g/cm³
- Equals 1000 kg/m³; water ≈ 1 g/cm³
One gram per cubic centimetre is exactly 1000 kilograms per cubic metre, so converting between the metric density units is just a power of ten.
Worked examples
Water
- Given
- 1 g/cm³
- Result
- 1000 kg/m³
Water’s density is almost exactly 1 gram per cubic centimetre, which is 1000 kilograms per cubic metre.
Steel
- Given
- 7.85 g/cm³
- Result
- ≈ 490 lb/ft³
Structural steel is about 7850 kg/m³, which converts to roughly 490 pounds per cubic foot.
Aluminium
- Given
- 2700 kg/m³
- Result
- ≈ 2.7 g/cm³
Aluminium is about a third the density of steel, which is why it is favoured where weight matters.
Frequently asked questions
It is close to that by historical design: the gram was originally defined as the mass of one cubic centimetre of water near its densest point. Water’s density is about 0.9982 g/cm³ at 20 °C, so 1 g/cm³ is a good round approximation at everyday temperatures.
Specific gravity is a material’s density divided by the density of water, so it is a dimensionless ratio. Because water is about 1 g/cm³, a material’s specific gravity is numerically close to its density in g/cm³. Steel’s specific gravity of ~7.85 matches its 7.85 g/cm³.
An object floats in a fluid if its average density is less than the fluid’s. Ice (about 0.92 g/cm³) floats on water; steel sinks unless shaped to trap enough air to lower its average density, which is how ships float.
Yes. The pound and inch have exact metric definitions, so pounds per cubic foot and per cubic inch convert exactly from kg/m³. The tool preserves full precision internally and rounds only for display.
For most materials, yes — they expand slightly when heated, lowering density. The effect is small for solids and liquids over ordinary ranges but significant for gases. These conversions treat density as a given value; they do not model temperature.
Related tools
Convert specific volume between m³/kg, ft³/lb, L/kg and cm³/g — the reciprocal of density.
Flow Rate ConverterConvert volumetric and mass flow rate, with density-based conversion between them.
Structural Steel & Lumber Weight CalculatorEstimate the weight of steel profiles and lumber from dimensions and reference densities.