Density
Definition
Mass per unit volume of a substance (ρ = m/V), typically measured in kg/m³ or g/cm³. Water's density is 1 g/cm³ or 1,000 kg/m³.
Why is Density Important?
Density is a core physics concept that describes the fundamental behavior of matter and energy. Understanding this principle enables engineers, students, and scientists to design better systems, solve real-world problems, and predict physical phenomena with precision.
Our physics calculators make it easy to compute values related to this concept, bridging the gap between theoretical understanding and practical application in engineering, education, and research.
What is Density?
Density (ρ) is the mass per unit volume of a substance: ρ = m/V. It tells you how tightly matter is packed together. Density determines whether objects float or sink, helps identify materials, and is fundamental in engineering, chemistry, and earth sciences.
Densities of Common Materials
| Material | Density (kg/m³) | Density (g/cm³) | Float in Water? |
|---|---|---|---|
| Air (at sea level) | 1.225 | 0.001225 | — |
| Styrofoam | 25–200 | 0.025–0.2 | Yes ✓ |
| Wood (oak) | 600–900 | 0.6–0.9 | Yes ✓ |
| Ice | 917 | 0.917 | Yes ✓ |
| Water | 1,000 | 1.000 | — |
| Concrete | 2,300 | 2.3 | No ✗ |
| Aluminum | 2,700 | 2.7 | No ✗ |
| Steel | 7,800 | 7.8 | No ✗ |
| Copper | 8,960 | 8.96 | No ✗ |
| Lead | 11,340 | 11.34 | No ✗ |
| Gold | 19,300 | 19.3 | No ✗ |
Why Density Matters
- Buoyancy: Objects less dense than the surrounding fluid float (ships, hot air balloons)
- Material identification: Unknown metal? Measure density to identify it
- Engineering: Aerospace prefers low-density materials (aluminum, carbon fiber)
- Cooking: Oil floats on water (oil density ~0.9 g/cm³ vs water 1.0)