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🧪 Density Converter

Convert between kg/m³, g/cm³, lb/ft³ and other density units

kg/m³1000
g/cm³1
g/mL1
lb/ft³62.427818
lb/in³0.036127
lb/gal8.345434
oz/in³0.578038

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Density Converter Instructions

The density converter supports conversion between seven commonly used density units: kg/m³, g/cm³, g/mL, lb/ft³, lb/in³, lb/gal, and oz/in³.

Density is the mass per unit volume of a substance, with the formula ρ = m/V (density = mass / volume). It is a core property for distinguishing different materials — an iron ball and a wooden ball of the same size have very different weights because iron has a much higher density. This tool covers metric, imperial, and US customary density units for engineering, research, and everyday needs.

Density Unit Conversion Relationships

【Metric (SI)】Base: kg/m³
1 g/cm³ = 1000 kg/m³ = 1 g/mL
1 g/mL = 1000 kg/m³ (water density ≈ 1 g/cm³)

【Imperial】
1 lb/ft³ ≈ 16.0185 kg/m³
1 lb/in³ ≈ 27679.9 kg/m³
1 lb/gal (US) ≈ 119.826 kg/m³
1 oz/in³ ≈ 1729.99 kg/m³

【Common Substance Densities】
Water (4°C): 1000 kg/m³ = 1 g/cm³
Iron: 7870 kg/m³ = 7.87 g/cm³
Gold: 19320 kg/m³ = 19.32 g/cm³
Air (sea level): 1.225 kg/m³
Mercury: 13546 kg/m³ = 13.546 g/cm³

Conversion Examples

📋
【Example 1】Steel weight calculation Steel plate 2m × 1m × 0.01m (10mm thick) Volume = 0.02m³ × iron density 7870 kg/m³ = 157.4 kg 【Example 2】Average human body density Approximately 985-1010 kg/m³ ≈ 0.98-1.01 g/cm³ Close to water density — so humans can almost float on water! Fat density ≈ 900 kg/m³ (less than water → floats) Muscle density ≈ 1060 kg/m³ (greater than water → sinks) 【Example 3】Oil-water separation Gasoline density ≈ 720 kg/m³ = 0.72 g/cm³ Diesel density ≈ 840 kg/m³ = 0.84 g/cm³ Cooking oil ≈ 920 kg/m³ = 0.92 g/cm³ All less than water (1 g/cm³), so oil always floats on water 【Example 4】Gold purity testing Pure gold density 19.32 g/cm³ If measured at 18.5 g/cm³ → gold content approximately 95.7%

Important Notes

💡
- Water has maximum density at 4°C (1000 kg/m³); it expands and density decreases at higher or lower temperatures - Seawater density (approximately 1025 kg/m³) is greater than freshwater, so people float more easily in seawater - "Specific Gravity" is the ratio of a substance's density to that of water at 4°C; it is dimensionless - Foam plastic density can be as low as 10-50 kg/m³ (mostly air) - Aviation fuel density changes significantly with temperature: approximately 804 kg/m³ at -40°C, approximately 770 kg/m³ at +40°C

Application Scenarios

  • - Materials science: Quickly identify unknown metals or alloy compositions through density
  • - Engineering calculations: Structural self-weight estimation, buoyancy design, container capacity planning
  • - Gemstone identification: Diamond density (3.51 g/cm³) vs. imitations (glass 2.5, zircon 5.6)
  • - Petroleum industry: Crude oil API gravity vs. density relationship, storage tank level-to-mass conversion
  • - Medical diagnostics: Bone density testing (DXA), body fat percentage measurement (underwater weighing)

The Fascinating World of Density

The densest known matter in the universe is the core of a neutron star — approximately 10^14 kg/m³, equivalent to compressing the Himalayas into the size of a sugar cube. The thinnest interstellar vacuum has a density of only about 10^-21 kg/m³ (a few hydrogen atoms per cubic meter), a difference of more than 10^65 times.

Among man-made materials on Earth, osmium has the highest density (22.59 g/cm³), more than twice that of lead (11.34). Interestingly, if the Earth were compressed to the same density, it would become a sphere with a radius of only 180 meters — but its mass would remain unchanged, and gravity would become terrifyingly intense. The simple ratio of m/V hides the deepest secrets of the material world.

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