How to use the Density Calculator
- Choose which of the three quantities you want to solve for.
- Enter the two you know, keeping mass in kilograms and volume in cubic metres.
- For litres, divide by 1,000 to get cubic metres; for grams, divide by 1,000 to get kilograms.
- Read the answer along with the specific gravity, which tells you at a glance whether the material floats in water.
- Use the pounds-per-cubic-foot figure for US material datasheets and shipping calculations.
How the calculation works
Density is mass per unit volume, and it is an intensive property: a gram of gold and a tonne of gold have the same density. That makes it a useful fingerprint for identifying materials and for checking whether a delivered load matches what was ordered, since a volume can be measured on site far more easily than a mass.
Specific gravity restates density as a dimensionless ratio against a reference — water at 998.2 kg/m³ at 20 °C for liquids and solids, air for gases. Because it is unitless, it survives translation between measurement systems intact, which is why it dominates in brewing, petroleum, concrete and laboratory work. Anything with a specific gravity below 1 floats in water; above 1 sinks.
Density varies with temperature and, for gases, strongly with pressure. Water peaks at 999.97 kg/m³ at 4 °C and falls as it warms, which is why hot-water tanks stratify. For gases the ideal gas law is the better tool, since density there is a function of state rather than a material constant. Porous solids also need a stated basis: bulk density includes the void space, true density does not, and quoting one where the other is meant is the standard error in aggregate ordering.
ρ = m ÷ V; m = ρ × V; V = m ÷ ρ; specific gravity SG = ρ ÷ 998.2 kg/m³ (water at 20 °C)Source: NIST Special Publication 811; CRC Handbook of Chemistry and Physics, 104th edition, density of water tables.
Worked example
A block of unknown metal has a mass of 8.9 kg and displaces 1.0 litre of water.
- Convert the volume: 1.0 L = 0.001 m³.
- Enter mass 8.9 and volume 0.001, solving for density.
- ρ = 8.9 ÷ 0.001 = 8,900 kg/m³, or 8.9 g/cm³.
- Compare against reference values: copper is 8,960 and nickel 8,908 kg/m³.
At 8,900 kg/m³ the block is almost certainly copper or nickel — and definitely not steel, which sits nearer 7,850.
Frequently asked questions
What is the density of water?+
998.2 kg/m³ at 20 °C, or a maximum of 999.97 kg/m³ at 4 °C. The convenient 1,000 kg/m³ is accurate to within 0.2% for most purposes.
Why does my aggregate delivery weigh less than calculated?+
You probably used true density rather than bulk density. Loose gravel is roughly 40% void space, so its bulk density is far below the density of the stone itself.
How do I get density in g/cm³?+
Divide kg/m³ by 1,000. The calculator shows both, and g/cm³ is numerically identical to specific gravity for practical purposes.
Does density change with temperature?+
Yes, though only slightly for solids and liquids — typically well under 1% over normal ambient ranges. For gases the change is large and the ideal gas law should be used instead.
Last reviewed September 1, 2026. We review this page whenever the underlying formula, tax year, published rate or standard changes.