Quick answer: Density is mass divided by volume: 27 g of aluminium filling 10 cm³ has ρ = 27 ÷ 10 = 2.7 g/cm³, which is 2,700 kg/m³.
How it's calculated
Density ρ = m ÷ V: how much mass is packed into each unit of volume. Rearranged, mass m = ρ × V and volume V = m ÷ ρ.
The calculator converts everything to kilograms and cubic metres first, then back to the unit you choose. 1 g/cm³ = 1 kg/L = 1,000 kg/m³, and 1 lb/ft³ = 16.018 kg/m³.
Density depends on temperature, and for gases on pressure too. Water is 1,000 kg/m³ at 4 °C and 998.2 kg/m³ at 20 °C; the values in the table are typical room-temperature figures.
Worked examples
- 27 g in 10 cm³: ρ = 27 ÷ 10 = 2.7 g/cm³ = 2,700 kg/m³
- Mass of 2 m³ of concrete at 2,400 kg/m³: m = 2,400 × 2 = 4,800 kg
- Volume of 1 kg of gold at 19,300 kg/m³: V = 1 ÷ 19,300 = 0.0000518 m³ = 51.81 cm³
Densities of common materials
| Material | kg/m³ | g/cm³ |
|---|---|---|
| Air (20 °C, sea level) | 1.204 | 0.001204 |
| Petrol (gasoline) | 740 | 0.74 |
| Olive oil | 910 | 0.91 |
| Ice | 917 | 0.917 |
| Water (4 °C) | 1,000 | 1 |
| Seawater | 1,025 | 1.025 |
| Concrete | 2,400 | 2.4 |
| Aluminium | 2,700 | 2.7 |
| Steel | 7,850 | 7.85 |
| Copper | 8,960 | 8.96 |
| Gold | 19,300 | 19.3 |
Frequently asked questions
What is the formula for density?
ρ = m ÷ V, mass divided by volume. Its SI unit is kg/m³; g/cm³ is also common and 1 g/cm³ = 1,000 kg/m³.
What is the density of water?
1,000 kg/m³ (1 g/cm³) at 4 °C, and 998.2 kg/m³ at 20 °C. Seawater is about 1,025 kg/m³.
What is specific gravity?
Density divided by the density of water (1,000 kg/m³). It has no unit: aluminium is 2.7, ice is 0.917, which is why ice floats.
Why does ice float?
Ice is about 917 kg/m³, a bit lighter than water, so it floats with roughly nine-tenths of it underwater. That's the tip-of-the-iceberg effect.
How do I find the density of an odd-shaped object?
Weigh it, then drop it into a measuring jug and see how far the water rises. Something weighing 27 g that pushes the water up 10 mL has a density of 2.7 g/cm³, which is aluminium.
What is the density of gold?
About 19.3 g/cm³. A 1 kg gold bar is only around 52 cm³, smaller than your phone.