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Convert between all major density units instantly. Comprehensive converter supporting kg/m³, g/mL, g/cm³, lb/ft³, and more.
| Material | kg/m³ | g/mL | lb/ft³ |
|---|---|---|---|
| Air (sea level, 15°C) | 1.225 | 0.001225 | 0.0765 |
| Hydrogen gas | 0.0899 | 0.00009 | 0.0056 |
| Cork | 240 | 0.24 | 15 |
| Pine wood | 500 | 0.5 | 31 |
| Oak wood | 600-900 | 0.6-0.9 | 37-56 |
| Ethanol | 789 | 0.789 | 49 |
| Ice | 917 | 0.917 | 57 |
| Water (4°C) | 1000 | 1.0 | 62.4 |
| Seawater | 1025 | 1.025 | 64 |
| Concrete | 2400 | 2.4 | 150 |
| Aluminum | 2700 | 2.7 | 169 |
| Titanium | 4540 | 4.54 | 283 |
| Steel | 7850 | 7.85 | 490 |
| Copper | 8960 | 8.96 | 559 |
| Lead | 11340 | 11.34 | 708 |
| Mercury | 13600 | 13.6 | 849 |
| Gold | 19300 | 19.3 | 1205 |
| Osmium (densest element) | 22590 | 22.59 | 1410 |
Density is a fundamental physical property that measures how much mass is contained in a given volume. Mathematically, it is defined as ρ = m/V (density equals mass divided by volume). Density is an intensive property, meaning it does not depend on the amount of material - a small piece of gold has the same density as a large bar of gold.
Materials Science: Density helps identify unknown materials, detect impurities, and verify product quality. Each pure substance has a characteristic density at a given temperature and pressure.
Engineering: Structural engineers use density to calculate loads, select materials, and estimate shipping weights. Aerospace engineers prioritize low-density materials to reduce aircraft weight.
Chemistry: Chemists use density to calculate molar masses, prepare solutions, and predict whether substances will float or sink. Density measurements help determine purity and concentration.
Environmental Science: Water density affects ocean currents and stratification. Air density varies with altitude and temperature, influencing weather patterns and atmospheric phenomena.
Temperature: Most materials expand when heated, causing density to decrease. Water is unusual - it is densest at 4°C, not at its freezing point.
Pressure: Gases are highly compressible, so their density increases significantly with pressure. Liquids and solids are nearly incompressible, showing minimal density change under normal pressures.
Composition: Alloys, mixtures, and solutions have densities that depend on their composition. For example, saltwater is denser than freshwater.
Phase: The same substance has different densities in different phases. Ice (0.917 g/mL) is less dense than liquid water (1.0 g/mL), which is why ice floats.
Ice floats because it is less dense than liquid water. When water freezes, its molecules form a crystalline structure with more space between molecules, causing the solid phase to be less dense (0.917 g/mL) than the liquid phase (1.0 g/mL). This unusual property is crucial for aquatic life - if ice sank, lakes and oceans would freeze from the bottom up, killing marine organisms.
For regular solids: Measure mass with a balance and calculate volume from dimensions, then divide mass by volume. For irregular solids: Use water displacement (Archimedes' principle) to measure volume. For liquids: Weigh a known volume in a graduated cylinder or use a hydrometer/densitometer for direct readings. For gases: Use specialized gas pycnometers or calculate from ideal gas law.
Osmium is the densest naturally occurring element with a density of 22.59 g/mL (22,590 kg/m³), slightly denser than iridium at 22.56 g/mL. Both are significantly denser than lead (11.34 g/mL) or gold (19.3 g/mL). These dense metals are used in specialized applications requiring maximum mass in minimal volume, such as fountain pen nibs and electrical contacts.
Altitude significantly affects gas density but has minimal effect on liquids and solids. Air density decreases with altitude because atmospheric pressure decreases - at 10,000 feet, air density is about 25% lower than at sea level. This affects aircraft performance, engine combustion, and HVAC system design. Denver, Colorado (the "Mile High City") has noticeably thinner air than coastal cities.
Objects float when their average density is less than the fluid they're in, and sink when denser. Ships made of steel (density 7.85 g/mL) float because their hull design creates a large volume of enclosed air, making the average density less than water (1.0 g/mL). Submarines control buoyancy by adjusting the amount of water in ballast tanks, changing their average density.
Specific gravity is the ratio of a substance's density to the density of a reference substance (usually water at 4°C for liquids and solids, or air for gases). Specific gravity is dimensionless (no units), while density has units. For example, mercury has a density of 13.6 g/mL and a specific gravity of 13.6 (compared to water at 1.0 g/mL). Specific gravity is convenient for quick comparisons.