Density Calculator
Find density, mass or volume from the other two.
About the Density Calculator
Density tells you how much mass is packed into a volume. It explains why a steel ship floats while a steel bolt sinks (the ship's average density, including the air inside, is lower than water's) and lets you identify a material or weigh a tank without a scale.
Enter any two of density, mass and volume to get the third. The calculator works in kg/m³ and also shows g/cm³ and lb/ft³. Water is about 1,000 kg/m³ (1 g/cm³); anything denser than the fluid around it sinks.
The formula
ρ = m ÷ V
- ρ
- density, in kilograms per cubic metre (kg/m³)
- m
- mass, in kilograms (kg)
- V
- volume, in cubic metres (m³)
Typical densities
| Material | kg/m³ | g/cm³ |
|---|---|---|
| Air (sea level, 20 °C) | 1.2 | 0.0012 |
| Ice | 917 | 0.917 |
| Fresh water (4 °C) | 1,000 | 1.000 |
| Sea water | ≈ 1,025 | ≈ 1.025 |
| Aluminium | 2,700 | 2.70 |
| Steel | ≈ 7,850 | ≈ 7.85 |
| Gold | 19,300 | 19.3 |
Values vary slightly with temperature, pressure and exact composition.
Worked example
What is this metal block?
- Mass 0.5 kg, volume 185 cm³ = 0.000185 m³
- ρ = 0.5 ÷ 0.000185 = 2,703 kg/m³
- That matches aluminium (2,700 kg/m³)
Things to keep in mind
- Convert units first: 1 cm³ = 0.000001 m³ and 1 litre = 0.001 m³.
- For a hollow or mixed object the answer is its average density, not that of the material.
Questions people ask
Does temperature change density?
Yes. Most substances expand when heated, so their density falls. Water is unusual: it is densest at about 4 °C, which is why ice floats.
What's specific gravity?
Density relative to water: ρ ÷ 1,000 kg/m³. Gold's specific gravity is about 19.3; it has no units.
How do I convert g/cm³ to kg/m³?
Multiply by 1,000. 2.7 g/cm³ is 2,700 kg/m³.